Kaplan Lecture Notes Step 2 CK

  • 91 1,177 7
  • Like this paper and download? You can publish your own PDF file online for free in a few minutes! Sign Up

Kaplan Lecture Notes Step 2 CK

Contents Chapter 1: The Newborn and Resuscitation. . . . . . . . . . . . • . . . . . . . . . . . . . . . . 1 Chapter 2:

2,215 554 8MB

Pages 329 Page size 578.16 x 771.12 pts Year 2008

Report DMCA / Copyright

DOWNLOAD FILE

Recommend Papers

File loading please wait...
Citation preview

Contents Chapter 1: The Newborn and Resuscitation. . . . . . . . . . . . • . . . . . . . . . . . . . . . . 1 Chapter 2: Genetics/Dysmorphology ................•..•............. 23 Chapter 3: Growth and Nutrition .................................... 35 Chapter 4: Development ........................................... 45 Chapter 5: Behavioral/Psychological Disorders. . . . . . . . . . . . . . . . . . . . . . . . . 51 Chapter 6: Immunizations .......................................... 57 Chapter 7: Child Abuse and Neglect ..................•............... 65 Chapter 8: Respiratory Disease ...................................... 73 Chapter 9: Allergy and Asthma ....•......•.....•.................... 87

I"'" Chapter 10: Immune-Mediated Disease ............................... 99 Chapter 11: Disorders of the Eye ..................................• 109 Chapter 12: Disorders of the Ear, Nose, and Throat. . . . . . . . . . . • . . . . . . .. 113 Chapter 13: Cardiology ...................................•....... 123 Chapter 14: Gastrointestinal Disease .........•...................... 149 Chapter 15: Renal and Urologic Disorders ...........................• 163 Chapter 16: Endocrine Disorders. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 175 Chapter 17: Orthopedic Disorders ................................... 185 Chapter 18: Rheumatic and Vasculitic Disorders ....................... 193 ~MEDICAL

V

Chapter 19: Hematology .......................................... 201 Chapter 20: Oncology ............................................ 215

""""

Chapter 21: Neurology ............................................ 225 Chapter 22: Infectious Disease ..................................... 241 Chapter 23: Introduction to Poisonings, Ingestions and Accidents ....... 269 Chapter 24: Adolescence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 285 Chapter 25: Dermatologic Conditions ............................. " 289

High-Yield Images ....................................................... 297 Index .................................................................... 311

"""'" ~,

""""

vi

~MEDICAL

The Newborn and Resuscitation APGAR SCORE Anewborn infant at birth is noted to have acrocyanosis, a heart rate of 140/ grimaces to stimulation, and is active and with a lusty cry. What is her Apgar score? Table 1-1. The Apgar Scoring System

rW;~aluation

"w"~h'M"""'.

"-",·,"v"",,

~

vw

'M~'_~~'~ ·,~v.

~.,

.-.""

."

,,''''''''''''

",~

,"

-~,

oPoints

1 Point

2 Points

0

lOO/min

Respiration

None

Irregular, shallow, gasps

Crying

Color

Blue

Pale, blue extremities

Pink

Tone

None

Weak, passive

Active

Facial grimace

Active withdrawal

: Heart rate

i

",,,,.,,"-'"

Reflex irritability

None

"',ww' ,,""'",

'",,,,,,

. 1

'c'

~"

re.

I

What You Need to Know About the Apgar Scoring System I~

(,"l1li\

• Apgar scores are routinely assessed at 1 and 5 minutes and every 5 minutes thereafter as long as resuscitation is continuing. • The l-minute score gives an idea of what was going on during labor and delivery, • The 5-minute score gives an idea of response to therapy (resuscitation). • In general, the Apgar score is not predictive of outcome; however, infants with scores of 0-3 at 5 minutes and longer compared to infants with scores of 7-10 have a worse neurologic outcome.

Other Routine Newborn Care Once the temperature is stable, cleanse the skin and umbilical cord with warm soap solution and then rinse the infant. Treat the cord with a bacteriocidal agent, such as triple dye or bacitracin. The eyes should then be treated with 1% silver nitrate drops or 0.5% erythromycin ophthalmic ointment. Administer 1 mg of vitamin K 1M to prevent hemorrhagic disease of the newborn. Order neonatal screening tests as needed (see Newborn Screening section). A hearing test should be given before discharge for ruling out congenital sensorineural hearing loss.

~MEDICAL

1

USMLE Step 2: Pediatrics

BIRTH INJURIES On physical exam, a 12-h-old newborn is noted to have nontender swelling of the head that does not cross the suture line. What is the most likely diagnosis? Table 1-2. Common Injuries During Deliveries r----,., _ _

.WW,. _ _ w,_w

Injury

I Subconjunctival (

hemorrhage

-

I

Specifics

Outcome

Common; sudden increase in intrathoracic pressure as chest passes through birth canal

Not a problem; will resolve

In utero from pressure against bones or forceps; linear: most common; depressed: elevate to prevent cortical injury; basilar: fatal (breech with traction on hyperextended spine with fixed head position)

Linear: no symptoms and no treatment needed

Erb-Dumenne: C5-C6; cannot shoulder abduct; externally rotate and supinate forearm; Klumpke: C7-C8 ± T1; paralyzed hand ± liornersyndrome

Most with full recovery; depends on whether nerve was injured or lacerated; full recovery over few months versus permanent damage; Rx: proper positioning and partial immobilization; massage and range of motion exercises; if no recovery in 3-6 mo, then neuroplasty

Especially with shoulder dystocia in vertex position and arm extension in breech

Palpable callus within a week; Rx: with immobilization of arm and shoulder

Entire side of face with forehead; forceps delivery or in utero pressure over facial nerve

Improvement over weeks (as long as fibers were not torn); need eye care; neuroplasty if no improvement (torn fibers) i

Diffuse edematous swelling of soft tissues of scalp; crosses suture lines

Disappears in first few days; may lead to molding for weeks

Subperiosteal hemorrhage: does not cross suture lines

May have underlying linear fracture; resolve in 2 wk to 3 mo; may calcify; jaundice

Difficult labor/delivery, perinatal asphxia, prolonged hypothermia

liypocalcemia

j

,, \

I Skull fractures !j

!!

1

I

Il Brachial palsy I

I

I ! !Clavicular fracture !

i

1

! Facial nerve palsy

I i Caputsuccedaneum

Cephalohematoma I

I

I Subcutaneous I fat necrosis -.------~~.

2

~PL~ MEDICAL

--"",,,.~~~~~

..

..

-.-~-.-~~,---.-~~ -~--,.---.

,( , ~

! I 1

The Newborn and Resuscitation

PHYSICAL EXAMINATION-NORMAL AND ABNORMAL FINDINGS Anewborn infant has ablue-gray pigmented lesion on the sacral area. It is clearly demarcated and does not fade into the surrounding skin. What is the most likely diagnosis? A newborn has a flat, salmon-colored lesion on the glabella, which becomes darker red when he cries. What is the best course of management?

(IIR' (IIR'

rfi'i"

Table 1-3. Physical Examination-Normal and Abnormal Findings '"

"¥",,,_-..~.,_,_,,5 number of fingers or toes. No treatment needed if good blood supply.

Finger tag

Thin stalk, poor circulation; tie off at base ~ auto amputation

~MEDICAL

The Newborn and Resuscitation

NEWBORN SCREENING A l-month-old fair-haired, fair-skinned baby presents with projectile vomiting of 4 days' duration. Physical exam reveals a baby with eaema and a musty odor. Which screening test would most likely be abnormal?

Newborn Screening • Every newborn before discharge or fourth day of life More reliable if done after 48 hours • Total diseases screened are determined by individual states. Some examples: ('F'

f""'-

Phenylketonuria Galactosemia Hypothyroidism

(0~ ~

Table 1-4. Comparison of Two Newborn Screening Diseases"" Phenylketonuria (P:Illi)

Classic Galactosemia

Defect

Phenylalanine hydroxylase; accumulation of PHE in body fluids and CNS

G-l-P uridylyltransferase deficiency; accumulation of G-l-P with injury to kidney, liver, and brain

Presentation

Mental retardation, vomiting, growth retardation, hyperactive, purposeless movements, athetosis, seizures

Jaundice (often direct), hepatomegaly, vomiting, hypoglycemia, cataracts, seizures, poor feeding, poor weight gain, mental retardation

Associations

Fair hair, fair skin, blue eyes, rash, tooth abnormalities, microcephaly

Predisposition to E. coli sepsis; developmental delay, speech disorders, learning disabilities

Other comments

Normal at birth; gradual MR over first few months

May begin prenataUytransplacental galactose from mother

Treatment

Low PHE diet for life

No lactose-reverses growth failure, kidney and liver abnormalities and cataracts, but not neurodevelopmental problems

--

,-.-",,-

Definition of abbreviations: eNS, central nervous system; G-I-P, galactose-I-phosphate; MR, mental retardation; PHE, phenylalanine. *Items in bold have a greater likelihood of appearing on the exam.

~PL~ MEDICAL

5

USMLE Step 2: Pediatrics

FETAL GROWTH AND MATURITY Table 1-5. Intrauterine Growth Restriction (IUGR)

--,-

\~.

! Type

!

Symmetric

!1

I,

Reason

Main Etiologies

Complications

Early, in utero insult that affects growth of most organs

Genetic syndromes, chromosomal abnormalities, congenital infections, teratogens, toxins

Etiology dependent; delivery of oxygen and nutrients to vital organs usually spared at expense of liver and subcutaneous tissue

I

Uteroplacental insufficiency secondary to maternal diseases (malnutrition, cardiac, renal, anemia) and/or placental dysfunction (hypertension, autoimmune disease, abruption)

Neurologic (asphyxia) if significant decreased delivery of oxygen to brain

II

I;

I \

Asymmetric (head 1 sparing) 1

I

I I I

!

1 L -__

6

~MEDICAL

Relatively late onset after fetal organ development; abnormal delivery of nutritional substances and oxygen to the fetus

I l

I

1

I

-

I

--~-~

(""'" ('Ii"' ~

The Newborn and Resuscitation

("'i'"

r-'" ,."..,

Ballard Scoring System

~

r-

ESTIMATION OF GESTATIONAL AGE BY MATURITY RATING Symbols: X - 1st Exam 0 - 2nd Exam

(P'"

r"""-

Side 1

Gestation by Dates _ _ _ _ _ _ _ _ _wks

tf"

t'" r'"

-1

r""'"

Posture

~

Square Window (wrist)

t"'" ('II'

t'"

am Birth Date _ _ _ _ _ _ Hour _ _ _ _ pm

NEUROMUSCULAR MATURITY 0

1

CJ?=;

90·

50·

~

45·

~80. 14~0. ~

Arm Recoil

4

3

c;ec: q::c: ~

rrr >90·

2

110·-140·

cL:J cb ~

c::6

~

5

o::r::

o· ito.

*

90·-110·

~ ~ 100·

Popliteal Angle

,."..,

Scarf Sign

~t

-(}

-~

-lB- -§ -§

Heel to Ear

G8 c:8

as

~

t9" I""'"

160·

140·

120·

MATURITY RATING

r

30·

,...

180·

APGAR _ _ _ _ _ _ _1 min _ _ _ _5 min

90·

score weeks

C:6

8-10 drinks/day

• Alcohol-most common teratogen to which fetus can be exposed • Findings-variable - Pre- and postnatal growth deficiency - Mental retardation - Fine motor dysfunction - Irritability in infancy, hyperactivity in childhood Behavioral abnormalities -

Mild to moderate microcephaly, short palpebral fissures, maxillary hypoplasia, short nose, smooth philtrum, thin and smooth upper lip Joint abnormalities-abnormal position and/or function Cardiac anomalies: VSD > ASD

Environmental • Fetal hydantoin syndrome

-

Similar features with prenatal exposure to carbamazepine, valproate, primidone, and phenobarbital No dose-response relationship has been demonstrated. Growth deficiency

-

Borderline to mild mental retardation Dysmorphic facial features Short neck Rib abnormalities

-

Abnormal palmar crease Hirsutism

-

30

~APL~ MEDICAL

Genetics/Dysmorphology

-

Cupid's-bow lips

Note

• Fetal valproate syndrome - Midface hypoplasia

• All females that will be treated with isotretinoin must do the following:

-

Cardiac defects

-

Long, thin fingers and toes; convex nails

-

Meningomyelocele

-

Cleft lip

• Retinoic acid embryopathy (from isotretinoin)

~

-

Mild facial asymmetry

-

Bilateral microtia/anotia (ear)

-

Facial nerve paralysis ipsilateral to ear

-

Narrow, sloping forehead

-

Abnormal mottling of teeth

-

Conotruncal malformations

-

CNS malformations

-

Decreased intelligence

-

Thymic and parathyroid abnormalities

-

No problems if stopped before 15 th postmenstrual day

-

All females of childbearing age must have pregnancy screening.

1. Pregnancy screening

2. One definitive method of birth control must be used (e.g., OCPs). 3. Must use one back-up method of birth control (e.g., condoms) 4. Receive counseling regarding teratogenicity

MISCELLANEOUS SEQUENCES

f"'I"

Potter Sequence

Note

• Etiology - Renal agenesis/dysgenesis or other type of urinary tract defect must occur prior to 31 days' gestation ~ oligohydramnios (also from chronic leakage) -

Leads to fetal compression Lack of alveolar sac development

~

pulmonary hypoplasia

• Findings - Pulmonary hypoplasia - Potter facies-hypertelorism, epicanthal folds, low-set ears, micrognathia, compressed flat nose, limb anomalies - Breech presentation - Abnormal positioning of hands and feet -

An ultrasound is necessary for the parents and siblings of patients with oligohydramnios secondary to agenesis and/or dysgenesis of both kidneys. This is because 9% of first-degree relatives have asymptomatic malformations.

Death from respiratory insufficiency

~MEDICAL

31

USMLE Step 2: Pediatrics

Moderate Short Stature With Facial Features but With or Without Genital Features Williams syndrome • Mild pre- and postnatal growth deficiency • Mild to moderate retardation • Friendly, talkative personality • Hoarse voice • Hypersensitivity to sound • Elfin facies - Prominent lips with open mouth -

Depressed nasal bridge

-

Periorbital fullness

-

Blue eyes, stellate pattern of eyebrows

-

Pointed ears

• Supravalvular aortic stenosis • Renal artery stenosis with hypertension • Joint limitations • lIypercalcernia

Noonan syndrome (Turner-like syndrome [also affects males]) • Postnatal short stature • Mental retardation (mild to moderate) • Many facial abnormalities • Low posterior hairline • Short or webbed neck • Shield chest and pectus excavatum • Cubitus valgus • Pulmonary valvular stenosis • Small penis, cryptorchidism • Bleeding diathesis-many defects

MISCELLANEOUS ASSOCIATIONS VACTERl Association • Nonrandom association of V = Vertebral defects A = Anal atresia (imperforate anus) C = Cardiac defects (VSD and others) T = TE fistula E = Esophageal atresia R = Renal defects L = Limb defects (radial)

32

~PL~ MEDICAL

GeneticsjDysmorphology

CHARG EAssociation • Nonrandom association of C = Coloboma (from isolated iris to anophthalmos; retinal most common) H = Heart defects (TOF, PDA, and others) A =Atresia choanae R = Retardation of growth and/or development G = Genital hypoplasia (in males) E = Ear anomalies and/or deafness

Prune Belly Syndrome • 95% of cases are male • Defect in mesodermal development - Genitourinary defects -

Absence of anterior abdominal wall muscles

-

Cryptorchidism

Peutz-Jeghers Syndrome • Autosomal dominant • 50% have no family history; high rate of spontaneous mutation • Pigmentation and polyps - Vertical bands of epidermal pigment appear as blue-gray or brownish spots on lips, oral mucous membranes, and periorally. -

Polyps can be found in jejunum, nasopharynx, bladder.

-

Spots appear in infancy to early childhood; fades in adults.

-

Up to 25% have an intussusception (also high percentage of GI problems and colicky abdominal pain).

-

Clubbing of fingers occasionally seen

Multiple Lentigines Syndrome (LEOPARD Syndrome) • Lentigines are 1-5-mm dark spots especially on neck and trunk; differ from freckles in that they are darker, are present at birth, are not related to sunlight, and increase in number with age L = Lentigines E = EKG abnormalities

o = Ocular hypertelorism P = Pulmonary stenosis A =Abnormalities of genitalia (hypogonadism, cryptorchidism) R = Retardation of growth D = Deafness (sensorineural)

~MEDICAL

11

/ females

Modifiable: o

Higher birth order

o

Shorter interpregnancy interval Less prenatal care

o

84

~MEDICAL

""""h,

Respiratory Disease

o

Low birth weight, preterm, intrauterine growth retardation

o

Maternal smoking

o

Postnatal smoking

• Sleep environment -

Higher incidence related to prone sleeping Supine position now better than side-lying No increased problems in supine Higher incidence with soft bedding/surfaces

-

Higher incidence with overheating

-

Pacifier shown to consistently decrease risk

• Other risk factors - Episode of an apparent life-threatening event (ALTE) Subsequent sibling of SIDS victim -

Prematurity-inverse with gestational age and birth weight

• SIDS cannot be prevented in individual infants because they cannot be prospectively identified. Home monitors do not decrease risk. • Reducing risk - Supine while asleep Use crib that meets federal safety standards -

No soft surfaces (sofas, waterbeds, etc.)

-

No soft materials in sleep environment

-

No bed-sharing

-

Avoid overheating and overbundling

-

Use prone position only while infant is awake and observed

-

No recommendation for home monitoring for this purpose

-

Expand national Back to Sleep campaign (up to 45% of infants still sleep prone).

~APL~ MEDICAL

85

Allergy and Asthma ALLERGIES

Allergic Rhinitis • Generally established by 6 years of age • Increased risk-early introduction of formula (versus breast milk) or solids, mother smoking before child is 1 year old, heavy exposure to indoor allergens • Most perennial or mixed • Increased symptoms with greater exposure • Diagnosis suggested by typical symptoms in absence of URI or structural abnormality (nasal congestion/pruritus, worse at night with snoring, mouth-breathing; watery, itchy eyes; postnasal drip with cough; possible wheezing; headache) • Specific behaviors - Allergic salute (rhinorrhea and nasal pruritus) -

~

nasal crease

Vigorous grinding of eyes with thumb and side of fist

• History of symptoms - Timing and duration (seasonal versus perennial) -

Exposures/settings in which symptoms occur Family history of allergic disease (atopy, asthma)

-

Ask about perennial versus seasonal

-

Seasonal allergies-usually need several seasons of exposure Food allergies more common (nuts, seafood) in young children (then skin, gastrointestinal, and, less often, respiratory)

• Physical examination - Allergic shiners (venous stasis)-blue-gray-purple beneath lower eyelids; often with Dennie lines-prominent symmetric skin folds - Conjunctival injection, chemosis (edema), stringy discharge, "cobblestoning" of tarsal conjunctiva - Transverse nasal crease (from allergic salute) - Pale nasal mucosa, thin and clear secretions, turbinate hypertrophy, polyps - Postnasal drip (posterior pharynx) - Otitis media with effusion is common • Differential diagnosis - Nonallergic inflammatory rhinitis (no IgE antibodies) - Vasomotor rhinitis (from physical stimuli)

~MEDICAL

87

USMLE Step 2: Pediatrics

-

Nasal polyps (think of CF)

-

Septal deviation

-

Overuse of topical vasoconstrictors

-

Neoplasms

-

Vasculitides

-

Granulomatous disorders (Wegener)

• Laboratory evaluation -

Note Differential Diagnosis of Eosinophilia • Neoplasms • Asthma/Allergy

In vitro: o Peripheral eosinophilia o

Eosinophils in nasal and bronchial secretions; more sensitive than blood eosinophils

o

Increased serum IgE

o

IgE-specific allergens:

• Addison disease • Collagen Vascular Disorders

~

RAST (radioallergosorbent testing)

~

Advantages: Safety Results not influenced by skin disease/medications

• Parasites

-

~

Major disadvantage: expensive; not as sensitive

~

Best use-extensive dermatitis, on medications that interfere with mast cell degranulation, high risk for anaphylaxis, cannot cooperate with skin tests

In vivo-skin test: o

Skin prick/puncture test

o

Use appropriate allergens for geographic area plus indoor allergens.

o

May not be positive before two seasons

--?

if negative but history suggests atopy --? intradermal

• Treatment-environmental control plus removal of allergen is most effective method -

Avoidance of biggest triggers-house dust mite, cat, cockroach Dehumidifiers, HEPA-filtered vacuuming, carpet removal, pillow and mattress encasement

-

Remove pets No smoking

-

No wood-burning stoves/fireplaces

• Pharmacologic control Antihistamines (first-line therapy):

-

88

~PL~ MEDICAL

o

First generation-sedating (diphenhydramine, chlorpheniramine, brompheniramine); cross blood-brain barrier-sedating

o

Second generation (cetirizine, fexofenadine, loratadine)-nonsedating (now preferred drugs); easier dosing

o

Oral antihistamines are more effective than cromolyn but significantly less than intranasal steroids; efficacy i when combined with an intranasal steroid

Intranasal corticosteroids-most effective medication, but not first-line: o

Effective for all symptoms

o

Add to antihistamine if symptoms are more severe

Allergy and Asthma

o

Less gastrointestinal absorption and safety with fiuticasone, mometasone, budesonide

Chromones---cromolyn and nedocromil sodium: o

Least effective

o

Very safe with prolonged use

-

Decongestants-(alpha-adrenergic -+ vasoconstriction}-topical forms (oxymetazoline, phenylephrine) significant rebound when discontinued.

-

Epinephrine-alpha and beta adrenergic effects; drug of choice for anaphylaxis Immunotherapy: o

Administer gradual increase in dose of allergen mixture -+ decreases or eliminates person's adverse response on subsequent natural exposure

o

Major indication-duration and severity of symptoms are disabling in spite of routine treatment (for at least two consecutive seasons). This, however, is the treatment of choice for insect venom allergy.

o

Should NOT be used for (lack of proof): • Atopic dermatitis • Food allergy • Latex allergy

o

• Urticaria • Children 6 months -

But most synthesize normally by 11 months

-

Extreme variability of immune system

• Increased incidence of otitis media and sinusitis-not life-threatening; responds to antibiotics; no IVIg needed

IgG subclass deficiency An 8-year-old girl complains of acute sore throat of 2 day's duration, accompanied by fever and mild abdominal pain. Physical examination reveals enlarged, erythematous tonsils with exudate and enlarged, slightly tender cervical lymph nodes. • One or more of the 4 subclasses are decreased despite a normal or even increased total IgG • Most are IgG2-also have 19A deficiency • May be an early marker for more general immune dysfunction • No Mg unless there are deficiencies of antibodies to broad array of antigens

Note

I~

Defects of Cellular Immunity (T cell Defects)

"DiGeorge Syndrome"

• More severe; no survival beyond infancy or early childhood (without definitive treatment)

DiGeorge syndrome A 3-week-old infant presents with a generalized seizure. The patient was born to a 22-year-old white woman, G1Pl, full term, via spontaneous vaginal delivery. The mother had good prenatal care and denies tobacco, drugs, and alcohol. There were no complications at delivery. The patient weighed 7 Ib 6 oz at birth and has gained weight. The infant has been feeding and sleeping well. On physical examination the patient has hypertelorism, low-set ears, micrognathia, and a fish mouth.

• T cells • Widely spaced eyes • Low-set ears • Fish mouth

• Treatment-transplantation of thymic tissue of MHC-compatible sibling or halfmatched parenteral bone marrow • Dysmorphogenesis of the third and fourth pharyngeal pouches -

Thymic hypoplasia

-

Parathyroid hypoplasia causes neonatal hypocalcemic seizures Tetany

-

Anomalies of great vessels (e.g., right aortic arch)

-

Other CHD (conotruncallesions, ASD, VSD)

-

Esophageal atresia

-

Bifid uvula Dysmorphic features (see margin illustration) o

Short philtrum

o

Hypertelorism

Note Other chromosome 22 microdeletion syndromes are the velocardial-facial syndrome and the conotruncal anomaly face syndrome. They are known as the CATCH-22 syndromes: ~ardiac, Abnormal facies, Ihymic hypoplasia, !:;Ieft palate, Hypocalcemia. ~ MEDICAL

103

USMLE Step 2: Pediatria

o

o

Mandibular hypoplasia Low-set, large, notched ears

• Microdeletion 22qll.2 • Decreased 19A and increased 19E • Low absolute lymphocyte count • Decreased CD3 T cells • Absent respiratory burst to mitogens • Decreased or absent thymic tissue with normal lymphoid tissue-partial to complete • Opportunistic infections-fungi, viruses, P. carinii • Graft-versus-host disease (GVHD); special care with blood transfusions

Combined Antibody and Cellular Defects Severe combined immunodeficiency (SClD) • Absence of all adaptive immune function and perhaps natural killer function • Classic presentation-first few months of life - Diarrhea - Pneumonia, otitis media, sepsis, cutaneous infections - Extreme wasting -' Opportunistic and viral infections (c. albicans, P. carinii, varicella, measles, parainfluenza 3, CMV [cytomegalovirus], EBV [Epstein-Barr virus])

Note Combined immunodeficiency's major difference from SCiD is the presence of low but not absent T-cell function.

-

GVHD from maternal immunocompetent T cells crossing placenta

-

Severe lymphopenia from birth

-

No mitogen response Small or no thymus, absent lymphoid tissue

-

No immunoglobulins No antibody responses

• Types - X-linked-most common -

Autosomal recessive-less common in United States than in Europe adenine deaminase (ADA) deficiency-lowest antibodies and lymphocyte counts

• Treatment-This is a true pediatric emergency ~ bone marrow transplant or death by 1 year of age

Note

-

Wiskott-Aldrich Syndrome:

If diagnosed in first 3 months of life, >95% treated successfully (more recentgene therapy)

Mr. Text IgMlow

Combined Immunodeficiencies

Recurrent infection

Wiskott-Aldrich syndrome

Ihrombocytopenia .Eczema X-linked 1- and B-cell deficiencies

104 ~PLA.!!>

MEDICAL

A l-year-old infant presents to his physician with severe eczema. On physical examination, the patient is noted to have draining ears as well as a petechial rash. Review of the medical record reveals that the patient has recurrent infections, including otitis media and pneumonia.

.-',

Immune-Mediated Disease

• X-linked recessive (WASP = Wiskott-Aldrich syndrome protein) • Findings - Atopic dermatitis (eczema) Thrombocytopenia with normal megakaryocytes but small defective platelets (petechiae) -

Susceptibility to infection (recurrent)

-

Palpable adenopathy

-

Splenomegaly and lympahdenopathies

• First-often prolonged bleeding from circumcision • First year-atopic dermatitis and recurrent infection; primarily polysaccharide encapsulated bacteria --+ pneumonia, meningitis, sepsis; later, P. carinii and herpes • Impaired humoral response-highly variable [Ig] -

Most with decreased IgM, increased 19A and 19E, and normal or slightly low IgG

• T cells moderately decreased and variable decreased mitogen response • Rare survival beyond teens without bone marrow transplant • Complications-malignancy, infections, bleeding

Ataxia-telangiectasia A 3-year-old child presents with ataxia, mask-like facies, drooling, tics, and irregular eye movements. According to the mother, the ataxia began at approximately 1 year of age. On examination of the patient's eyes, he is noted to have telangiectasias. In addition, he also has a history of recurrent respiratory infections. A-T mutation on chromosome 11; protein kinase

• Moderate decrease in response to B- and T-cell mitogens • Decreased CD3 and CD4 cells • Variable humoral and cellular deficiency-most with selective 19A deficiency • Hypoplastic thymus --+ helper T-cell defects o Physical examination: ~

Mask-like facies

~Tics

-

~

Drooling

~

Irregular eye movements

Progressive cerebellar ataxia-from beginning of walking; wheelchair by 10-12 years old Oculocutaneous telangiectasias-begin at 3-6 years old Chronic sinopulmonary disease, common viral infections-usually do well Complications-High incidence of malignancies---Iymphoreticular but also adenocarcinoma

~PLA,!!) MEDICAL

105

USMLE Step 2: Pediatrics

OTHER IMMUNE DEFICIENCIES

Phagocytic Defects Note Suspect eGO in a newborn with prolonged detachment of the umbilical cord.

Chronic granulomatous disease (CGO) X-linked and autosomal recessive Neutrophils and monocytes can ingest but not kill catalase-positive microorganisms -

Findings: o

Recurrent lymphadenitis, pneumonia, skin infections

o

Hepatic abscesses

o

Osteomyelitis at multiple sites

o

Family history of recurrent infection

o

Unusual infections with catalase-positive organisms: ~

S. aureus (most)

~

S. marcescens B. cepacia Aspergillus C. albicans Salmonella

~ ~

~ ~

Diagnosis-NBT now replaced by more accurate flow cytometry test using dihydrorhodamine 123 fluorescence (DHR test) -

Treatment-bone marrow transplant and daily TMP-SMZ

leukocyte adhesion deficiency (LAO-l and LAO-2)-rare autosomal recessive -

Impairment in neutrophil function

-

Infancy-recurrent bacterial infections of skin, mouth, respiratory tract, genital mucosa ~ chronic ulcers S. aureus, enteric gram-negatives, fungal No typical signs of inflammation or pus Diagnosis-flow cytometry of surface CD 11 b Treatment-bone marrow transplant

Chediak-Higashi syndrome-rare autosomal recessive -

Characteristics: o Recurrent infection o

Mild bleeding diathesis-increased bleeding time

o

Partial oculocutaneous albinism

o

Progressive peripheral neuropathy

o

Life-threatening lymphomas

Defective neutrophil degranulation

106 ~PL~ MEDICAL

o

Oversized, dysmorphic lysosomes, storage granules, or vesicular structures ~ decreased content of hydrophilic enzymes

o

Infections-mucous membrane, skin, and respiratory

"'""',

Immune-Mediated Disease

• Gram-positive, gram-negative, and fungi • Most common is S. aureus -

Diagnosis-large inclusions in all nucleated RBCs on Wright-stained blood, but accentuated by peroxidase

-

Treatment-high-dose ascorbate; only cure = bone marrow transplant

Myeloperoxidase (MPO) deficiency -

Deficiency of oxidative metabolism-missense mutation o MPO = green heme protein in azurophilic lysosomes of neutrophils and monocytes; basis for green tinge to pus o Leads to decreased hypochlorous acid and decrease in killing of gram-positive and gram-negative organisms (rarely disseminated Candida)

-

Usually clinically silent

~PL~ MEDICAL

107

tj ~ ~.J .~

~ ~I .~

~ ~

l ~ 1~

~

~ ~

~

""')

Disorders of the Eye EYE EXAM-IMPORTANT POINTS • How do you measure visual acuity at different ages? -

Infant-fixation and following (acuity 20/200-20/400; see black and white better)

-

4 years, 20/30; 5-6 years, 20/20

ABNORMALITIES OF THE EYE STRUCTURES Pupils and iris

Note

• Aniridia • Myopia Hyperopia -

Bilateral in almost all Panocular-macular and optic nerve hypoplasia, lens and cornea

r-

20% of sporadics develop WJlms tumor (usually by age 3)

~

o

fO"

Wilms Tumor Aniridia yenitourinary malformations Retardation

Screen with ultrasound until 5 years old

Coloboma of iris -

Often autosomal dominant

fO"

-

Defect of lid, iris, lens, retina, or choroid

r--

-

Always inferior-keyhole appearance of iris; in lid, manifests as cleft

Leucokoria f'I".

r-"

-

Retinoblastoma

-

Cataract Retinopathy of prematurity

f"1lJIA

(8"~

r~

-

Retinal detachment

-

Larval granulomatosis

Lens • Cataracts-lens opacities; what are the most important congenital etiologies? -

Prematurity (many disappear in a few weeks)

-

Inherited-most autosomal dominant

r-

Congenital infection-TORCH (especially rubella); also, measles, polio, influenza, varicella, vaccinia

,-.,

-

Galactosemia Chromosomal (trisomies, deletions and duplications, XO)

r-"

-

Drugs, toxins, and trauma (steroids, contusions, penetrations)

~ MEDICAL

109

USMLE Step 2: Pediatrics

Note Amblyopia ("Lazy Eye'1 Hirschberg test: looks for corneal reflex and determines misalignment.

• Ectopia lentis-instability or displacement of lens; edge of displaced lens may be visible in pupillary aperture - Differential: o Trauma-most common o

Uveitis, congenital glaucoma, cataract, aniridia, tumor

o

Systemic causes ~ Marfan syndrome (most with superior and temporal; bilateral) ~ Homocystinuria-inferior and nasal ~ Ehlers-Danlos

Cover test: covering of good eye forces lazy eye to move into position.

Ocular muscles • Strabismus - Definition-Misalignment of the eyes from abnormal innervation of muscles -

Note

Diagnosis-Hirschberg corneal light reflex-most rapid and easily performed; light reflex should be symmetric and slightly nasal to center of each pupil

• Pseudostrabismus - Caused by unique facial characteristics of infant

Chemical: first day Gonorrhea: first week Chlamydia: second week (most common)

"""",

• Transient pseudostrabismus - Common up to 4 months of age

Conjunctiva • Ophthalmia neonatorum

Note • Congenital nasolacrimal duct obstruction (dacryostenosis) - Failure of canalization of duct as it enters the nose

A 12-hour-old newborn is noted to have bilateral conjunctival injection, tearing, and some swelling of the left eyelid. Physical examination is otherwise normal. -

Redness, chemosis, edema of eyelids, purulent discharge

-

Causes: o

- Excessive tears, mucoid material that is produced in the lacrimal sac, erythema

o o

~ o

~

-

Topical erythromycin does

not prevent chlamydia conjunctivitis.

110 ~

MEDICAL

Mild inflammatory and serosanguineous discharge, then thick and purulent Complications-corneal ulceration, perforation, iridocyclitis

C. trachomatis-5-14-day incubation; most common

From mild inflammation to severe swelling with purulent discharge Mainly tarsal conjunctivae; cornea rarely affected Diagnosis-Gram stain, culture, tarsal scraping for Giemsa stain (intracytoplasmic inclusions), and PCR (polymerase chain reaction) for chlamydia Treatment: o N. gonorrhea: ceftriaxone x 1 dose 1M + saline irrigation until clear o Chlamydia: erythromycin PO x 2 weeks + saline irrigation until clear (may prevent subsequent pneumonia) ~

-

Note

N. gonorrhea-2-5-day incubation; may be delayed >5 days due to suppression from prophylactic eye treatment ~

- Treatmentnasolacrimal massage 2-3x/day and warm water cleansing - Most resolve girls Race-more in Native Americans, Inuit, indigenous Australians SES-more with poverty Genetic-heritable component Breast milk versus formula-protective effect of breast milk Tobacco smoke-positive correlation Exposure to other children-positive correlation Season-cold weather Congenital anomalies-more with palatal clefts, other craniofacial anomalies, and Down syndrome

• Etiology - Bacterial in up to 75% o

s. pneumonia (40%)

o

NontypeableH. influenza (25-30%)

o

Moraxella catarrhalis (10-15%)

- Other 5o/o-Group A strep, S. aureus, gram negatives (neonates and hospitalized very young infants), respiratory viruses (rhinovirus, RSV most often) • Pathogenesis - Interruption of normal eustachian tube function (ventilation) by obstruction --+ inflammatory response --+ middle ear effusion --+ infection; most with URI - Shorter and more horizontal orientation of tube in infants and young children allows for reflux from pharynx • Clinical findings-highly variable - Symptoms-ear pain, fever, purulent otorrhea (ruptured tympanic membrane), irritability, or no symptoms - Pneumatic otoscopy-fullness/bulging or extreme retraction, intense erythema (otherwise erythema may be from crying, fever, sneezing; erythema alone is insufficient unless intense), some degree of opacity (underlying effusion) - Mobility is the most sensitive and specific factor to determine presence of a middle ear effusion • Treatment-It is advisable to use routine antimicrobial treatment especially for 95% for age, need further evaluation Etiology-essential (primary) or secondary - Secondary-most common in infants and younger children ~

o

Newborn-umbilical artery catheters

renal artery thrombosis

o

Early childhood-renal disease, coarctation, endocrine, medications

o

Adolescent-essential hypertension

- Renal and renovascular hypertension-majority of causes may be due to urinary tract infection (secondary to an obstructive lesion), acute glomerulonephritis, Henoch-Schonlein purpura with nephritis, hemolytic uremic syndrome, acute tubular necrosis, renal trauma, leukemic infiltrates, mass lesions, renal artery stenosis

146 ~

MEDICAL

-,

cardiology

- Essential hypertension-more common in adults and adolescents o

Positive family history

o

Multifactorial-obesity, genetic, and physiologic changes

Diagnosis Screening tests-CBC, urinalysis, urine culture, electrolytes, glucose, BUN, creatinine, calcium, uric acid; lipid panel with essential hypertension and positive family history Echocardiogram for chronicity (left ventricular hypertrophy) - Renal ultrasound, scan Angiography-plasma renin activity in renal veins and inferior vena cava (IVe). Peripheral plasma renin activity (PRA)-useful screen for renovascular and renal disorders Treatment If obese-weight control, aerobic exercise, no-added-salt diet, monitor blood pressure Pharmacologic treatment (secondary hypertension and selective primary) o Often first choice in essential hypertension (of a younger child) is diuretic or beta blocker o If not sufficient-calcium channel blocker added to diuretic; ACE inhibitor (good in high-renin hypertension secondary to renovascular or renal disease; also for high-renin essential hypertension) may replace the beta blocker o Adolescent with significant hypertension-eonsider initial treatment with ACE inhibitor and calcium channel blocker o Neonates-partial renal vascular occlusion ~ captopril (because of increased angiotensin) o Neural crest tumors with circulating catecholamines ~ alpha blocker (phentolamine, phenoxybenzamine) and beta blocker to control heart rate, or agent with dual action (labetalol)

~APLA'!y MEDICAL

147

Gastrointestinal Disease ORAL CAVITY Teeth Discolored teeth - Fluorosis-mottled enamel (white patches to brown discoloration and hypoplasia); from high fluoride content of drinking water, large amounts of swallowed toothpaste, inappropriate fluoride treatment - Tetracyclines if given during enamel formation (from 4 months' gestation to 7 years of age); brown-yellow discoloration with hypoplasia; repeated and/or prolonged treatment Delayed eruption of primary teeth-hypopituitarism, hypothyroidism, trisomy 21, rickets, and certain syndromes Natal teeth-usually two mandibular central incisors; present at birth (neonatal teeth erupt in first month); positive family history or syndromes; decision for removal is individualized Dental caries-causes - S. mutans--adheres to enamel, produces acid, and fosters further demineralization - Sucrose is most cariogenic (bottle-propping; sticky candy) Genetic predisposition - Treatment-decrease incidence with fluoride and brushing

Cleft lip and Palate Most are multifactorial inheritance; also autosomal dominant in families (most with isolated cleft palate)

Note "Rule of lOs" for Correction of Cleft Lip

Clefts are highest among Asians, lowest among African descent

• 10 weeks

Increase in other malformations with isolated cleft palate

• 10lb

Most important early issue is feeding (special nipple needed) Complications-increased risk of otitis media, hearing loss, speech problems Treatment-surgical correction - Lip at 3 months of age

• 10 mgldL Hb

- Palate at 50% of small bowel with or without a portion of the large intestine (presence of ileocecal valve is better)

Celiac Disease Associated with exposure to gluten, rye, wheat, barley Patients mostly 6 months to 2 years of age Permanent intolerance Genetic predisposition (RLA DQ2) Clinical presentation

Note Abetalipoproteinemia - severe fat malabsorption form birth - acanthocyes - very low to absent plasma cholesterol, triglycerides, etc.

- Diarrhea - Failure to thrive - Growth retardation - Vomiting - Anorexia, not interested in feeding

- Ataxia ~APL~ MEDICAL

153

USMLE Step 2: Pediatrics

Evaluation - Antiendomysial and antigliadin antibodies - Histologic confirmation is mandatory (gold standard) Treatment-lifelong, strict gluten-free diet

VOMITING Esophageal Atresia and Tracheoesophageal Fistula (rEF)

A

B

c

o

Figure 14-1. Tracheosophageal Fistula

Most common anatomy is upper esophagus ends in blind pouch and TEF is connected to distal esophagus

Note VACTERL Association Nonrandom association of birth defects: ~ertebral

anomalies

Anal atresia

Half with associated anomalies-VACTERL association Clinical presentation in neonate Frothing, bubbling, cough, cyanosis, and respiratory distress - With feedings

~

immediate regurgitation and aspiration - Identified with first feed

.cardiac defect IracheoEsophageal fistula

Diagnosis - Inability to pass nasogastric/orogastric tube

Renal anamolies

- X-ray shows tube coiled with air-distended stomach

Limb abnormalities

154 ~

H-type--presents chronically and diagnosed later in life with chronic respiratory problems

- For isolated TEF-esophagram with contrast media (or bronchoscopy or endoscopy with methylene blue) Treatment-surgical ligation of TEF and resection with end-to-end anastomosis of esophageal atresia

MEDICAL

Gastrointestinal Disease

Gastroesophageal Reflux Disease (GERD) A 4-month-old is admitted with episodes of apnea occurring 20-30 min after feeds. The mother states the baby has been spitting up since birth. She is at the fifth percentile for weight. Etiology-insufficient lower esophageal sphincter tone early in life Symptoms during first few months of life; peaks at 4 months; resolves by 12-24 months of age; in older children-chronic (more like adults); only half resolve completely Clinical presentation - Postprandial regurgitation - Signs of esophagitis-arching, irritability, feeding aversion, failure to thrive - Obstructive apnea, stridor, lower airway disease (cough, wheezing) Diagnosis - Most by history and physical - Barium esophagram and upper gastrointestinal studies - Esophageal pH monitoring (best test)-quantitative and sensitive documentation of acid reflux (normal pH in lower esophagus is 100,000 colonies/mL (single pathogen) or if symptomatic with> 10,000 colonies/mL Treatment - Lower-urinary tract infection (cystitis) with amoxicillin, trimethoprim-sulfamethoxazole, or nitrofurantoin ~PLA'!y MEDICAL

163

USMLE Step 2: Pediatrics

Pyelonephritis needs initial intravenous antibiotic treatment and total of 14 days of oral antibiotics-start with intravenous ceftriaxone or ampicillin plus gentamicin Follow up Do urine culture 1 week after stopping antibiotics to confirm sterility; periodic reassessment for next 1-2 years

~,

Obtain ultrasound with febrile UTI for anatomy, abscess, hydronephrosis Obtain voiding cystourethrogram (VCUG) in:

° All males ° All females 5 years old with second UTI - Renal scan (Tc-Iabeled DMSA [dimercaptosuccinic acid]) for scarring and renal size (most sensitive and accurate study, but not first choice)

VESICOURETERAL REFLUX (VUR) A 2-year-old girl presents with urinary tract infection. She has had mUltiple urinary tract infections since birth but has never had any follow-up studies to evaluate these infections. Physical examination is remarkable for an ill-appearing child who has a temperature of 40 0 ( (104°F) and is vomiting. Definition-abnormal backflow of urine from bladder to kidney Etiology - Occurs when the submucosal tunnel between the mucosa and detrusor muscle is short or absent. - Predisposition to pyelonephritis ---7 scarring ---7 reflux nephropathy (hypertension, proteinuria, renal insufficiency to end-stage renal disease [ESRD], impaired kidney growth) Grading

- Grade I: into nondilated ureter - Grade II: upper collecting system without dilatation - Grade III: into dilated collecting system with calyceal blunting - Grade N: grossly dilated ureter and ballooning of calyces - Grade V: massive; significant dilatation and tortuosity of ureter; intrarenal reflux Diagnosis - VCUG for diagnosis and grading

--

\

- Renal scan for renal size and scarring; if scarring, follow creatinine Natural history - Increased scarring with higher grades - Grade I or II resolves regardless of age at diagnosis or whether it is unilateral or bilateral - With growth, tendency to resolve (lower> higher grades); resolve by age 6-7 years; grade V rarely resolves

164 ~

MEDICAL

.-.,

\

Renal and Urologic Disorders

Treatment - Medical-based on reflux resolving over time; most problems can be taken care of nonsurgically - Continuous antibiotic prophylaxis-either sulfamethoxazole/trimethoprim, trimethoprim alone, or nitrofurantoin in % to 1/3 dose - Surgery if: o Any breakthrough UTI o

New scars

o

Failure to resolve, or bilateral grades N - V

OBSTRUCTIVE UROPATHY Definition-obstruction of urinary outflow tract Clinical presentation - Hydronephrosis - Upper abdominal or flank pain Pyelonephritis, UTI - Weak, decreased urinary stream - Failure to thrive, diarrhea (or other nonspecific symptoms) Diagnosis - Palpable abdominal mass in newborn; most common cause is hydronephrosis or polycystic kidney disease - In boys with bladder obstruction-walnut-shaped mass (bladder) above pubic symphysis (posterior urethral valves) - Most can be diagnosed prenatally with ultrasound. - First indication in newborn is often infection or sepsis. - Obtain VCUG in all cases of congenital hydronephrosis and in any with ureteral dilatation to rule out posterior urethral valves - Further studies with renal scan - CT scan for suspected ureteral calculi Common etiologies Ureteropelvic junction obstruction-most common - Ectopic ureter-2 months after onset

MEDICAL

\

Complications - Hypertension - Acute renal failure - Congestive heart failure

166 ~

--

Renal and Urologic Disorders

- Electrolyte abnormalities - Acidosis - Seizures Uremia Treatment - Antibiotics for 10 days (penicillin) - Sodium restriction, diuresis - Fluid and electrolyte management - Control hypertension (calcium channel blocker, vasodilator, or angiotensinconverting enzyme inhibitor) - Complete recovery in >95%

Other Glomerulonephritides IgA Nephropathy (Berger disease) Most common chronic glomerular disease worldwide Clinical presentation - Most commonly presents with gross hematuria in association with upper respiratory infection or gastrointestinal infection - Then mild proteinuria, mild to moderate hypertension

- Normal C3 Most important primary treatment is blood pressure control.

Alport Syndrome The school nurse refers a 7-year-old boy because he failed his hearing test at school. The men in this patient's family have a history of renal problems, and a few of his maternal uncles are deaf. A urinalysis is obtained from the patient, which shows microscopic hematuria. Hereditary nephritis (X-linked dominant); renal biopsy shows foam cells Asymptomatic hematuria and intermittent gross hematuria 1-2 days after upper respi-

ratory infection Hearing deficits (bilateral sensorineural, never congenital) females have subclinical hearing loss

Ocular abnormalities (pathognomonic is extrusion of central part of lens into anterior chamber

Benign Familial Hematuria Autosomal dominant due to mutation in type IV collagen Diffuse thinning of glomerular basement membrane seen on biopsy r""""

(""" ~

Reassurance, overall excellent prognosis

Membranous Glomerulopathy Most common cause of nephrotic syndrome in adults (see Nephrotic section)

f". fI"'.

~ MEDICAL

167

USMLE Step 2: Pediatrics

Membranoproliferative Glomerulonephritis Most common cause of chronic glomerulonephritis in older children and young adults

lupus Nephritis Varying clinical presentations Treatment depends on type of renal disease but usually includes steroids +/- irnmunomodulators

Henoch-Schonlein Purpura Small vessel vasculitis with good prognosis Present with purpurie rash, joint pain, abdominal pain Most resolve spontaneously; antiinflammatory medications, steroids

Hemolytic Uremic Syndrome (HUS) A 3-year-old child presents to the emergency center with history of bloody diarrhea and decreased urination. The mother states that the child's symptoms began 5 days ago after the family ate at a fast-food restaurant. At that time the patient developed fever, vomiting, abdominal pain, and diarrhea. On physical examination, the patient appears ill. He is pale and lethargic. Most common cause of acute renal failure in young children Microangiopathic hemolytic anemia, thrombocytopenia, and uremia Most from E. coli 0157:H7 (shiga toxin-producing) - Most from undercooked meat or unpasteurized milk; spinach - Also from Shigella, Salmonella, Campylobaeter, viruses Pathophysiology - Subendothelial and mesangial deposits of granular, amorphous material-vascular occlusion, glomerular sclerosis, cortical necrosis - Capillary and arteriolar endothelial injury ~ localized clotting

- Mechanical damage to RBCs as they pass through vessels - Intrarenal platelet adhesion and damage (abnormal RBCs and platelets then removed by liver and spleen) - Prothrombotic state Clinical presentation - Most common ~

~ ~

Endocrine Disorders EVALUATION OF GROWTH Definitions Growth velocity-yearly increments of growth; should follow a growth curve Chronologie age (CA)-actual age Bone age (BA)-x-ray ofleft hand and wrist

Situations CA=BA

- With normal growth velocity-ideal - With abnormal growth velocity-genetic, chromosomal, endocrine abnormality CA>BA

- With normal growth velocity-constitutional delay - With abnormal growth velocity-chronic systemic disease, endocrine disorders CAecreasedgrowth ~ Diabetes insipidus o If there is an expanding tumor: ~ headache ~ vomiting ~ visual changes ~ decreased school performance ~ papilledema ~ cranial nerve palsies Laboratory evaluation - Screen for low serum insulin-like growth factor (IGF)-l and IGF-binding protein-3 (IGF-BP3) I>efinitive test-growth-hormone stimulation test Examine other pituitary function: o Thyroid-stimulating hormone (TSH) o

o

T4 Adrenocorticotropic hormone (ACTH), cortisol, dehydroepiandrosterone (I>HEA) sulfate, gonadotropins, and gonadal steroids

Other studies - X-ray most helpful with destructive lesions (enlargement of sella, erosions) - Calcification - Bone age-skeletal maturation markedly delayed (BA 75% of CA) MRI is indicated in all patients with hypopituitarism. (superior to CT scan)

Note If there is a normal response to hypothalamic-releasing hormones, the pathology is located within the hypothalamus.

Differential diagnoses (the major ones) - Systemic conditions (Weight is often proportionally much less than height.) - Constitutional delay - Genetic short stature (BA = CA, short parents) ~PL~ MEDICAL

177

USMLE Step 2: Pediatrics

- Primary hypothyroidism - Emotional deprivation (psychosocial dwarfism) Treatment - Classic growth-hormone deficiency-weekly recombinant growth hormone - Need periodic thyroid evaluation-develop reversible hypothyroidism Indications-growth hormone currently approved in United States for Documented growth-hormone deficiency - Turner syndrome - End-stage renal disease before transplant - Prader-Willi syndrome - Intrauterine growth retardation (IUGR) without catch-up growth by 2 years of age

Tall Stature Definition-accelerated growth rate; may provide a clue to an underlying disorder Differential diagnosis - Familial taIl stature (most common) - Fetal overgrowth-infant of diabetic mother (IODM), Beckwith-Wiedemann syndrome, cerebral gigantism (Sotos syndrome) - Postnatal--exogenous obesity, excess growth hormone secretion, precocious puberty, Marfan syndrome, hyperthyroidism, XXY, XYY, fragile X

Hyperpituitarism Note

Primary-rare

If the history suggests anything other than familial tall stature or obesity, or if there are positive physical findings, then the patient needs laboratory evaluation.

- Most are adenomas - Most commonly secrete corticotropin Secondary - Deficiencies of target organ - Excessive prolactin (most common) and growth hormone secretion Laboratory evaluation - Screen-IGF-l and IGF-BP3 for growth hormone excess; confirm with a glucose suppression test Need MRI of pituitary - Chromosomes especially in a male (decreased upper- to lower-body segment ratio suggests XXY; mental retardation suggests fragile X) - Thyroid tests Management - Treatment only if prediction of adult height (based on BA) >3 SD above the mean or if there is evidence of severe psychosocial impairment - Trial of sex steroids (accelerates puberty and epiphyseal fusion)

Precocious Puberty Definition - Girls-sexual development 4 years, may need surgery

Talipes Equinovarus (Clubfoot) A newborn is noted to have a foot that is stiff and slightly smaller than the other one. The affected foot is medially rotated and very stiff, with medial rotation of the heel. •

Congenital, positional, or associated with neuromuscular disease



Hindfoot equinus, hindfoot and midfoot varus, forefoot adduction



Treatment - Complete correction should be achieved by 3 months (serial casting, splints, orthoses, corrective shoes); if not, then surgery

Note

In talipes equinovarus, the patient's heel can't go flat on the exam surface (as opposed to metatarsus adductus, in which the heel can).

- Can't get heel flat on examination surface

Internal Femoral Torsion (Femoral Anteversion) •

Most common cause of intoeing ~2 years of age



Most are secondary to abnormal sitting habits (W-sitting).

• •

Entire leg rotated inwardly at hip during gait Treatment-observation; takes 1-3 years to resolve; surgery only if significant at >10 years of age

Internal Tibial Torsion •

Most common cause of intoeing 2 em at skeletal maturity usually require surgery.

DISORDERS OF THE KNEE Popliteal Cyst (Baker Cyst) Typical in middle childhood Distension of bursa by synovial fluid behind knee Ultrasound for aspiration Observe if 10 years of age)

Osgood-Schlatter Disease Traction apophysitis of tibial tubercle (overuse injury) Look for active adolescent Swelling, tenderness, increased prominence of tubercle Treatment-rest, restriction of activities, knee immobilization, isometric exercises Complete resolution requires 12-24 months

DISORDERS OF THE SPINE Scoliosis A 12-year-old girl is seen for routine physical examination. She voices no complaints. Examination is remarkable for asymmetry of the posterior chest wall on bending forward. One shoulder appears higher than the other when she stands up. Most are idiopathic; rarely, hemivertebra Others are congenital, with neuromuscular disorders, compensatory, or with intraspinal abnormalities. Slightly more females than males; more likely to progress in females

188 ~PLA!y

MEDICAL

I

Orthopedic Disorders



Adolescent (>11 years) more common



Adams test-almost all with >20-degree curvature are identified in school screening programs (but many false positives) Diagnosis-x-ray is standard: posterior/anterior and lateral of entire spine Treatment-trial brace for immature patients with curves 45 degrees (permanent internal fixation rods)

DISORDERS OF THE NECK

Torticollis Twisted neck; head tipped to one side, chin rotates to other side Etiologies - In utero positioning, labor trauma - Later-trauma, inflammatory, CNS neoplasm Treatment - Gentle passive stretching in first few months of life Surgery should be performed before development of secondary facial asymmetries.

DISORDERS OF THE UPPER LIMB

Nursemaid Elbow •

When longitudinal traction causes radial head subluxation History of sudden traction or pulling on arm Physical exam reveals a child who refuses to bend his/her arm at the elbow Treatment-rotate hand and forearm to the supinated position with pressure of the radial head ~ reduction

fD'

~

OSTEOMYELITIS AND SEPTIC ARTHRITIS Etiology

Note

- Osteomyelitis:

S. aureus most common overall o Neonate-GBS and Gram negatives o Pseudomonas-puncture wound o Salmonella-sickle cell - Septic arthritis: o Almost all S. aureus o Most in young children; hematogenous Presentation - Pain with movement in infants - Older-fever, pain, edema, erythema, warmth, limp, or refusal to walk Diagnosis - Blood culture, CBC, ESR, C-reactive protein (CRP) o

X-rays for patients with osteomyelitis are initially normal. Changes are not seen until 10-14 days.

~ MEDICAL 189

USMLE Step 2: Pediatrics

- Radiographic studies: o

Initial plain film to exclude other causes-trauma, foreign body, tumor; trabecular long bones do not show changes for 7-14 days (septic arthritis shows widening of joint capsule and soft-tissue edema)

o

Ultrasound-joint effusion, guide localization of drainage Best test is MRI; very sensitive and specific

o o

Bone scan-can be valuable to augment MRI, especially if multiple foci are suspected

o

Definitive-aspirate for Culture and Sensitivity ~

Osteomyelitis ~ bone biopsy for culture and sensitivity

~

Septic arthritis ~ ultrasound guided arthrocentesis for culture and sensitivity

Treatment - Antibiotics-always cover for Staphylococcus initially o

Septic arthritis-treatment for 4 weeks

o

Osteoarthritis-treatment for 4 to 6 weeks

OSTEOGENESIS IMPERFECTA Susceptibility to fracture of long bones or vertebral compression from mild trauma Most common genetic cause of osteoporosis All types are caused by structural or quantitative defects in type I collagen. Autosomal dominant Clinical triad is fragile bones, blue sclera, and early deafness. Four types - Type I-mild; fractures from mild to moderate trauma; decreases after puberty - Type II-perinatally lethal; stillborn or die in first year; multiple intrauterine fractures of long bones; small thorax - Type III-progressive deforming; most severe nonlethal form; all have scoliosis and vertebral compression - Type IV-moderately severe; usually have ambulatory community skills; fracture rates decrease after puberty Diagnosis - Rule out child abuse due to fracture and injury history. - Confirmed by collagen biochemical studies using fibroblasts cultured from a skinpunch biopsy - May see fractures on prenatal ultrasound as early as 6 weeks Treatment-no cure; physical rehabilitation; fracture management and correction of deformities

""""\ 190 ~

MEDICAL

f"'"

Orthopedic Disorders

BONE TUMORS Malignant Osteogenic sarcoma most common (if patient is younger than 10 years, then Ewing sarcoma more common) Predisposition-retinoblastoma, irradiation (osteogenic) versus none (Ewing) Diagnosis-x-ray shows sclerotic destruction; sunburst (osteogenic) versus lytic with laminar periosteal elevation (Ewing) Metastases-lung and bone for both Treatment-chemotherapy, ablative surgery (osteogenic) versus radiation and/or surgery (Ewing) Prognosis

- Without metastases: o

Osteogenic-70% cure

o

Ewing-600/0 cure

- With metastases:

~

o

Osteogenic- ~20%

o

Ewing-20-300/0

Table 17.1. Osteogenic Sarcoma Versus Ewing Sarcoma Osteogenic Sarcoma

Ewing Sarcoma

Presentation

Second decade

Second decade

Race

All

Mostly white

M:F

Slightly greater in males

Slightly greater in males

Predisposition

Retinoblastoma, radiation

None

X-ray

Sclerotic destruction: "sunburst"

Lytic with laminar periosteal elevation: "onion skin"

Metastases

Lungs, bone

Lungs, bone

Treatment

Chemotherapy, ablative surgery

Radiation and/or surgery

Note Codman's triangle is seen in those with osteogenic sarcoma. It is due to periosteal bone formation at the diaphysis.

i

I !i I 1

! j

! Outcome without metastases at diagnosis

70% cure

60% cure

Outcome with metastases

:5:20%

20-30%

~PL~ MEDICAL 191

.~.

~ ~ ~ ~

~ .~

~

~ .~ ..-

/~ )

~

~ /~

~ ~

~ ~.

~

~ ~ ~

~ .~

~ i~

Rheumatic and Vasculitic Disorders JUVENILE RHEUMATOID ARTHRITIS (IDIOPATHIC RHEUMATOID ARTHRITIS) A7-year-old girl has been complaining of pain and swelling of the left wrist and right knee off and on for the past 3 months. She has been previously healthy. The pain is worse in the morning and improves throughout the day. Physical examination is remarkable for swelling and effusion of the right knee, with decreased range of motion. • Definition-idiopathic synovitis of peripheral joints associated with soft-tissue swelling and joint effusion • Pathophysiology - Vascular endothelial hyperplasia and progressive erosion of articular cartilage and contiguous bone - Immunogenetic susceptibility and an external trigger - HLA DR4 increased with polyarticular disease; DRS and DRS with pauciarticular disease • Clinical presentation - Morning stiffness - Easy fatigability - Joint pain later in the day, joint swelling, joints warm with decreased motion, and pain on motion, but no redness • Criteria for diagnosis - Age of onset: 1.5 cm

o

Other findings:

o

~

Extreme irritability

~

Aseptic meningitis

~

Diarrhea

~

Hepatitis

~

Hydrops of the gallbladder

~

Urethritis with sterile pyuria

~

Otitis media

~

Arthritis

Note Any child suspected of having Kawasaki disease should have an echocardiogram.

Cardiac findings: ~

Early myocarditis (50%) with tachycardia and decreased ventricular function

~

Pericarditis

~

Coronary artery aneurysms in the second to third week

• Lab abnormalities - WBC-normal to increased; neutrophils and bands - Increased ESR, C-reactive protein (CRP) at 4-8 weeks - Normocytic anemia - Platelets high/normal in week 1, then significant increase in weeks 2-3 (often more than a million) - Sterile pyuria - Increased hepatic transaminases - Cerebrospinal fluid (CSF) pleocytosis ~PL~ MEDICAL

197

~.

USMLE Step 2: Pediatrics

Note

• Diagnosis-most important test is 2D echocardiogram; repeat at 2-3 weeks and, if normal, at 6-8 weeks. Also get ECG, follow platelets.

Kawasaki disease is one of the few instances in pediatrics for which you would use aspirin. (It is usually avoided because of the risk of developing Reye syndrome.)

• Treatment - Convalescent: o

Acute-intravenous immunoglobulin (Mg)

o

High-dose aspirin

o

Use of steroids limited to persistent fever

o

Low-dose aspirin (3-5 mglkglday)

o

Add warfarin if at risk for thrombosis (very high platelet counts)

• Prognosis-no evidence of long-term cardiovascular sequelae in those who do not have coronary abnormalities within 2 months of onset

HENOCH-SCHONLEIN PURPURA (HSP) A 5-year-old boy is seen with maculopapular lesions on the legs and buttocks. He complains of abdominal pain. He has recently recovered from a viral upper respiratory infection. Complete blood cell count, coagulation studies, and electrolytes are normal. Microscopic hematuria is present on urine analysis. • IgA-mediated vasculitis of small vessels (lgA and C3 in skin, renal glomeruli, and gastrointestinal tract); most common cause of nonthrombocytopenic purpura in children • Usually follows an upper respiratory infection • Children usually 2-8 years of age; usually in winter, more males than females • Clinical presentation - Low-grade fever and fatigue - Hallmark-pink, maculopapular rash below waist; progresses to petechiae and purpura (red -+ purple -+ rusty brown); crops over 3-10 days (at times in intervals up to 3-4 months) - Gastrointestinal: o

Intermittent abdominal pain

o

Occult blood in stools

o

Diarrhea or hematemesis

o

Intussusception may occur

- Arthritis unusually large, weight-bearing joints - Renal-2S-S0% with glomerulonephritis or nephrosis - Hepatosplenomegaly, lymphadenopathy - Rarely, CNS (seizures, paresis, coma) • Laboratory studies - Increased platelets, WBCs, ESR - Anemia - Increased 19A, IgM - May have anticardiolipin or antiphospholipid antibodies - Urine-RBCs, WBCs, casts, albumin

198 ~PL~

MEDICAL

-.

Rheumatic and Vasulitic Disorders

• Diagnosis - Classic clinical presentation - Definitive diagnosis (rarely needed) with skin biopsy - Renal biopsy shows IgA mesangial deposition and occasionally IgM, C3, and fibrin • Treatment - Symptomatic treatment for self-limited disease (constitutional symptoms, rash, arthritis) - Intestinal complications-corticosteroids oral or intravenous ~ dramatic improvement of gastrointestinal signs and symptoms (can recur for as long as 3 years) Renal-same for any form of renal disease - If anticardiolipin or APL antibodies and/or thrombotic events-ASA • Complications-renal insufficiency/failure, bowel perforation, scrotal edema, and testicular torsion; chronic renal insufficiency occurs in 5 lobes in a peripheral smear.

• Peaks at 4-7 months of age-irritability, failure to thrive, chronic diarrhea • Cause-inadequate intake (pregnancy, goat milk feeding, growth in infancy, chronic hemolysis), decreased absorption or congenital defects of folate metabolism • Differentiating feature-low serum folate Treatment-daily folate; transfuse only if severe and symptomatic

Vitamin

B12

(Cobalamin) Deficiency

• Only animal sources; produced by microorganisms (humans cannot synthesize) • Sufficient stores in older children and adults for 3-5 years; but in infants born to mothers with deficiency, will see signs in first 4-5 months • Inadequate production (extreme restriction [vegans]), lack of intrinsic factor (congenital pernicious anemia [rare], autosomal recessive; also juvenile pernicious anemia [rare] or gastric surgery), impaired absorption (terminal ileum disease/removal)

Note If autoimmune pernicious anemia is suspected, remember the Schilling test and antiparietal cell antibodies.

• Clinical-weakness, fatigue, failure to thrive, irritability, pallor, glossitis, diarrhea, vomiting, jaundice, many neurologic symptoms Labs-normal serum folate and decreased vitamin Bl2 • Treatment-parenteral Bl2

~APLA'!y MEDICAL 205

USMLE Step 2: Pediames

Table 19.2. Comparison of Folic Acid Versus Vitamin B12 Deficiencies .

! \ Food sources I

!t I, Presentation

.",-.,..,."~.N""""",,,_.,_-""".H"""~.~N_~._~,h''''''

Vitamin B12 (Cobalamin) Deficiency

Green vegetables, fruits, animals

Only from animals, produced by microorganisms

Peaks at 4-7 months

Older children and adults with sufficient stores for 3-5 years

I

;

i

Infants born to mothers: first signs 4-6 months

!i

Goat milk feeding

Inadequate production (vegans)

i

Chronic hemolysis

Congenital or juvenile pernicious anemia (autosomal recessive, rare)

I

ICauses !

Decreased absorption Congenital defects of folate metabolism

I

I

,

\

Gastric surgery Terminal ileum disease

Findings

Low serum folate with normal to increased iron and vitamin Bl2

Normal serum folate and decreased vitamin B12

Treatment

Daily folate

Parenteral vitamin B12

l

!

Folic Acid Deficiency

-~

___J

HEMOLYTIC ANEMIAS

Hereditary Spherocytosis and Elliptocytosis • Most autosomal dominant • Abnormal shape ofRBC due to spectrin deficiency ~ decreased deformability ~ early removal of cells by spleen • Clinical presentation - Anemia and hyperbilirubinemia in newborn - Hypersplenism, biliary gallstones - Susceptible to aplastic crisis (parvovirus B12) • Labs - Increased reticulocytes - Increased bilirubin - Hb 6-10 mg/dL - NormalMCV - Increased mean cell Hb concentration (MCHC) - Smear-spherocytes or elliptocytes diagnostic • Diagnosis - Blood smear, family history, increased spleen size - Confirmation~smotic fragility test • Treatment-transfusions, splenectomy (after 5-6 years), folate

206 ~

MEDICAL

Hematology

Enzyme Defects Pyruvate kinase (glycolytic enzyme) • Wide range of presentation - Some degree of pallor, jaundice, and splenomegaly - Increased reticulocytes, mild macrocytosis, polychromatophilia • Diagnosis-protein kinase (PK) assay (decreased activity) • Treatment-exchange transfusion for significant jaundice in neonate; transfusions (rarely needed), splenectomy

Glucose-6-phosphate dehydrogenase (G6PD) A2-year-old boy presents to the physician's office for an ear check. The child had an ear infection that was treated with trimethaprim-sulfamethoxazole 3 weeks earlier. On physical examination, the patient is noted to be extremely pale. Hb and Hct were obtained and are noted to be 7.0 g/dL and 22%, respectively. • Two syndromes - Episodic hemolytic anemia (most common) - Chronic nonspherocytic hemolytic anemia • X-linked; a number of abnormal alleles • Episodic common among Mediterranean, Middle Eastern, African, and Asian ethnic groups; wide range of expression varies among ethnic groups • Within 24-48 hours after ingestion of an oxidant (acetylsalicylic acid, sulfa drugs, antimalarials, fava beans) or infection and severe illness ~ rapid drop in Hb, hemoglobinuria and jaundice (if severe) • Acute drop in Hb, saturated haptoglobin bodies, increased reticulocytes

~

free Hb and hemoglobinuria, Heinz

• Diagnosis-direct measurement of G6PD activity • Treatment-prevention (avoid oxidants); supportive for anemia

HEMOGLOBIN DISORDERS Sickle Cell Anemia (Homozygous Sickle Cell or S-Beta Thalassemia) A 6-month-old, African-American infant presents to the pediatrician with painful swollen hands and swollen feet. • Occurs in endemic malarial areas • Single base pair change (thymine for adenine) at the sixth codon of the beta gene (valine instead of glutamic acid) Clinical presentation - Newborn usually without symptoms; development of hemolytic anemia over first 2-4 months (replacement of HbF); by 6 months, may have functional asplenia (by age 5 years, almost all will) ~ MEDICAL

207

USMLE Step 2: Pediatrics

- First presentation usually hand-foot syndrome (acute dactylitis)-symmetric, painful swelling of hands and feet (ischemic necrosis of small bones) - Acute painful crises: o

Younger-mostly extremities

o

With increasing age-head, chest, back, abdomen

o

Precipitated by illness, fever, hypoxia, acidosis, or without any factors

- More extensive vaso-occlusive crises ~ ischemic damage o

Skin ulcers

o

Retinopathy

o

Avascular necrosis of hip

o

Infarction of bone and marrow (increased risk of Salmonella osteomyelitis)

o

Splenic autoinfarction

o

Pulmonary-acute chest syndrome (along with sepsis, are most common causes of mortality)

o

Stroke (peak at 6-9 years of age) Priaprism, especially in adolescence

o

- Acute splenic sequestration (peak 6 months to 3 years of age); can rapidly lead to death Altered splenic function ~ increased susceptibility to infection, especially with encapsulated bacteria (S. pneumococcus, H. injluenzae, N. meningitidis) Aplastic crisis-after infection with parvovirus B19; absence of reticulocytes during acute anemia o

Cholelithiasis-symptomatic gallstones

Kidneys-decreased renal function (proteinuria first sign); urinary tract infections Labs

o

o

Increased reticulocytes

o

Mild to moderate anemia

o

NormalMCV

o

Nucleated RBCs

o

If severe anemia: ~

Smear-target cells, poikilocytes, hypochromasia, sickle RBCs, nucleated RBCs, Howell-Jolly bodies (lack of splenic function)

~

Bone marrow markedly hyperplastic

Diagnosis o Confirm diagnosis with Hb electrophoresis (best test) o

Note Patients without a functioning spleen are predisposed to infection with encapsulated organisms, and therefore, pneumococcal vaccination is highly suggested.

208 ~

Newborn screen; use Hb electrophoresis

Prenatal diagnosis for parents with trait • Treatment o

MEDICAL

Prevent complications: Immunize (regular plus 23-valent pneumococcal)

o

o

Start penicillin prophylaxis at 2 months

o

Educate family (assessing illness, palpating spleen, etc.) Folate supplementation

o

Hematology

- Aggressive antibiotic treatment of infections - Pain control - Transfusions as needed - Monitor for risk of stroke with transcranial Doppler - Hydroxyurea - Bone-marrow transplant

THALASSEMIAS Beta Thalassemia Major (Cooley Anemia) A 9-year-old has a greenish-brown complexion, maxillary hyperplasia, splenomegaly, and gallstones. Her Hb level is 5.0 g/dL; and she has an MCV of 65 mL. • Excess alpha globin chains ~ alpha tetramers form; increase in HbF (no problem with gamma-chain production) • Presents in second month of life with progressive anemia, hypersplenism, and cardiac decompensation (Hb 10 years

Supratentorial

Diffuse astrocytoma

__.--1

Infratentorial Tumors Benign astrocytoma A lO-year-old child presents to the physician because of anew onset seizure. The patient has a l-month history of severe headache and a progressively worsening wide-based gait • Most common • Low-grade, rarely invasive • Most common-juvenile pilocytic astrocytoma - Classic site-cerebellum - Surgery, radiation, and/or chemotherapy - With complete resection, 80-100% survival

Malignant astrocytoma Anaplastic • Glioblastoma multiforme-poor outcome

Medulloblastoma • Embryonal tumors-medulloblastoma

A6-year-old child presents to the pediatrician because of headache and persistent emesis for the past week that is not associated with fever or abdominal pain. • Second most common Mostly males ages 5-7 years • Most midline cerebellar vermis • Solid, homogeneous mass in posterior fossa-fourth ventricular obstruction, hydrocephalus • Radiation and chemotherapy-60-700/0 survival

218 ~

MEDICAL

Oncology

Brain-stem tumors A 9-year-old child is brought to the physician by her parents because of personality change. The parents state that over the past month the child has become very aggressive, i.e., arguing, hitting, and biting other children. Her grades have dropped from straight As to failing. This behavior is quite out of character for their intelligent, outgoing, and friendly daughter. • Third most common • Motor weakness, cranial nerve defects, cerebellar defects, signs of increased ICP - Low-grade gliomas-surgery - Diffuse intrinsic-poor outcome: o

Radiation-mean survival 12 months

o

Palliative chemotherapy

Ependymal tumors A 5-year-old child presents to the emergency center because of neck stiffness and torticollis for the past 3 days. The patient also has vomiting, headache, and papilledema. • Ependymal lining of ventricles • Most common ependymoma - Most in posterior fossa - 10% spread - Well circumscribed, mostly noninvasive - Surgery and radiation

Supratentorial Tumors Craniopharyngioma A 14-year-old girl presents to the physician because of short stature. On physical examination, the patient is found to have bitemporal visual field defects. A head a scan shows calcification at the sella turcica. • Most common; 7-10% of all • • • •

Suprasellar Minimal invasiveness Calcification on x-ray Major morbidity-panhypopituitai."ism, growth failure, visual loss

• Surgery and radiation; no role for chemotherapy

~PL~ MEDICAL

219

USMLE Step 2: Pediatrics

Optic nerve glioma A 4-year-old boy with neurofibromatosis presents to the ophthalmologist with complaints of decreased visual acuity according to his parents. On physical examination, the patient has proptosis and papilledema. • Classified as a juvenile pilocytic astrocytoma • Most frequent tumor of the optic nerve • Benign, slowly progressive • Unilateral visual loss, proptosis, eye deviation, optic atrophy, strabismus, nystagmus - Increased incidence in neurofibromatosis - Treatment-observation: o If chiasm is involved-radiation/chemotherapy o

Surgery if proptosis with visual loss

OTHER MALIGNANCIES Wilms Tumor A mother brings her 3-year-old child to the physician because she found an abdominal mass while bathing the child. The child has been in her usual state of health according to the mother. However, on review of the vital signs, the patient is noted to have an elevated blood pressure. • Nephroblastoma • Second most common malignant abdominal tumor - Usual age 2-5 years - One or both kidneys (bilateral in 7%) - Associations: o Hemihypertrophy o

Aniridia

o Genitourinary anomalies • Clinical presentation-asymptomatic abdominal mass • Diagnosis - Abdominal CT scan best test

- Chest x-ray for lung involvement • Treatment - Surgery - Then chemotherapy (vincristine and dactinomycin) and radiation (same if inoperable) - Bilateral renal-unilateral nephrectomy and partial contralateral nephrectomy • PrognosiS-54 to 97% have 4-year survival

220 ~

MEDICAL

~\

Oncology

Neuroblastoma A 2-year-old child is brought to the physician because of bluish skin nodules, periorbital proptosis, and periorbital ecchymosis that have developed over the last few days. On physical examination, a hard smooth abdominal mass is palpated.

Note Patients with neuroblastoma can present with ataxia or opsomyoclonus ("dancing eyes and dancing feet"). These patients may also have Horner syndrome.

• From neural crest cells, due to N-myconcogene; can occur at any site • 8% of childhood malignancies • Most are - Abdominal - Adrenal - Retroperitoneal sympathetic ganglia • 30% are cervical, thoracic, or pelvic ganglia • Firm, palpable mass in flank or midline; painful; with calcification and hemorrhage • Initial presentation often as metastasis-long bones and skull, orbital, bone marrow, lymph nodes, liver, skin • Diagnosis - Plain x-ray, CT scan, MRI - Elevate urine homovanillic acid (HVA) and vanillylmandelic acid (VMA) in 95% of cases - Evaluate for spread-bone scan, bone marrow (neuroblasts) - Staging-from I (organ of origin) to IV (disseminated) • Treatment - Surgery - Chemotherapy (cyclophosphamide and doxorubicin) - Radiation - Bone marrow - Stem cell transplant

Note

Pheochromocytoma • Catecholamine-secreting tumor from chromaffin cells • Most common site-adrenal medulla, but can occur anywhere along abdominal sympathetic chain; also bladder, urethral walls, thorax, cervical • Children age 6-14 years; more on the right side; >20% are bilateral, and some with multiple tumors • Autosomal dominant; associated with neurofibromatosis, MEN-2A and MEN2B, tuberous sclerosis, Sturge-Weber syndrome, and ataxia-telangiectasia • Clinical presentation - Episodic hypertension, palpitations and diaphoresis, headache, abdominal pain, dizziness, pallor, vomiting, sweating, encephalopathy - Hypermetabolic state, polyuria and polydipsia, growth failure

Children with pheochromocytoma excrete predominantly norepinephrine-increased VMA and metanephrine. Children with neuroblastoma usually do not have hypertension, and major metabolites are dopamine and HVA.

- Retinal examination-papilledema, hemorrhages, exudate ~APL~ MEDICAL

nl

USMLE Step 2: Pediatrics

• Labs-significant increase in blood or urinary levels of catecholamines and metabolites • Diagnosis - Most tumors can be localized by CT scan (best initial test) and MRI, but extraadrenal masses are more difficult. - Can use 1131 metaiodobenzylguanidine (MBIG) scan -+ taken up by chromaffin tissue anywhere in body • Treatment-removal, but high-risk - Preoperative alpha and beta blockade and fluid administration - Need prolonged follow up; may manifest later with new tumors

Rhabdomyosarcoma A mother brings her 3-year-old daughter to the physician for evaluation because the young girl has "grapes" growing out of her vagina. • More than 50% are soft-tissue sarcomas • Almost any site, which determines presentation - Head and neck-40% - Genitourinary tract-20% - Extremities--200/0 - Trunk-lO% - Retroperitoneal and other-lO% • Increased frequency in neurofibromatosis • Determination of specific histologic type needed for assessment and prognosis Types - Embryonal-60% o

Intermediate prognosis

Botryoid {projects; grapelike)-vagina, uterus, bladder, nasopharynx, middle ear - Alveolar-15% o

o

Trunk and extremities

o

Very poor prognosis

- Pleomorphic-adult form; very rare in children • Clinical presentation - Mass that mayor may not be painful - Displacement or destruction of normal tissue - Easily disseminates to lung and bone • Diagnosis-depends on site of presentation - Biopsy - MRI - CT scan - Ultrasound

2n

~PLA,!!) MEDICAL

""""',

Oncology

- Bone scan, marrow aspirate, and biopsy - Lymph node biopsy • Treatment-best prognosis with completely resected tumors (but most are not completely resectable) - Chemotherapy pre- and postoperatively - Local radiation

~ MEDICAL

223

.~ I

~,

~

f'I'" ("""~ ~

f'I'" (fIi'>--

f'I'"

Neurology

fiI' (fIi'>--

fiI'

f'I'" fiI'

CENTRAL NERVOUS SYSTEM (eNS) ANOMALIES Neural Tube Defects • Elevated alpha-fetoprotein is a marker.

Spina bifida occulta • Midline defect of vertebral bodies without protrusion of neural tissue • Most asymptomatic and of no clinical consequence • Occasionally associated with other anomalies • May have overlying midline lumbosacral defect (patch of hair, lipoma, dermal sinus)

Tethered cord • Ropelike filum terminale persists and anchors the conus below L2 • Abnormal tension--asymmetric lower extremity growth, deformities, bladder dysfunction, progressive scoliosis, diffuse pain, motor delay • Most associated with a midline skin lesion • Plain x-rays show spina bifida in most; MRI needed for precise anatomy • Surgical transection

Meningocele • Meninges herniate through defect in posterior vertebral arches • Fluctuant midline mass well covered with skin; may transilluminate • Must determine extent of neural involvement with MRI - CT scan of head for possible hydrocephalus - Immediate surgery if there is only a thin cover or leak of CSF

Myelomeningocele The pediatrician is called to the delivery room because an infant is born with a defect in the lumbosacral area. • Strong evidence that maternal periconceptional use of folate reduces risk by half • May occur anywhere along the neuraxis, but most are lumbosacral • Low sacral lesions-bowel and bladder incontinence and perineal anesthesia without motor impairment ~PL~ MEDICAL

225

USMLE Step 2: Pediatrics

• Midlumbar lesion---sacIike cystic structure covered by thin, partially epithelized tissue - Flaccid paralysis below the level of the lesion is most common; no deep tendon reflexes (DTRs), no response to touch and pain Urinary dribbling, relaxed anal sphincter • 80% associated with hydrocephalus; type I Chiari malformation-may have symptoms of hindbrain dysfunction (feeding difficulty, choking, stridor, apnea, vocal cord paralysis, upper extremity spasticity) • Evaluation and treatment - Must evaluate for other anomalies prior to surgery Evaluate renal function Head CT scan for possible hydrocephalus Treatment-ventriculoperitoneal shunt and correction of defect

Hydrocephalus A 2-month-old infant is noted to have a head circumference greater than the 95th percentile.

• Definition--impaired circulation and absorption of CSF or, rarely, from increased CSF production from a choroid plexus papilloma • Types - Obstructive (noncommunicative) versus nonobstructive (communicative) from obliteration of subarachnoid cisterns or malfunction of arachnoid villi

Note

o

Almost every child with a sacral or lumbar spine lesion will achieve some form of functional ambulation, and half of those with higher spine defects will have some degree of hip flexor and hip adductor movement

Obstructive-most are obstructive from abnormalities of the cerebral aqueduct (stenosis or gliosis; congenital, intrauterine infection, mumps, hemorrhage) or lesions near the fourth ventricle (brain tumor, Chiari malformation, Dandy-Walker malformation)

- Nonobstructive-occurs mostly with subarachnoid hemorrhage; also with pneumococcal or TB meningitis or leukemic infiltrates • Clinical presentation-depends on rate of rise of intracranial pressure - Infants: o

Increased head circumference

o

Bulging anterior fontanel

o

o

Distended scalp veins Broad forehead "Setting sun" sign Increased DTRs

o

Spasticity, clonus

o o

- Older child: o Subtler o o

o o

226 ~PL~

MEDICAL

Irritability Lethargy Poor appetite Vomiting

Neurology

o

Headache

o

Papilledema

o

Sixth-nerve palsy

• Treatment for all types of hydrocephalus--shunting

Chiari malformation Type II - Progressive hydrocephalus with myelomeningocele - Abnormality of hindbrain

Dandy-Walker malformation • Cystic expansion of fourth ventricle • Associated agenesis of posterior cerebellar vermis and corpus callosum • Presents with increasing head size and prominent occiput, long-tract signs, cerebellar ataxia, and delayed motor development

Note Type I Chiari Malformation • Displacement of cerebral tonsils into cervical canal from obstruction of caudal fourth ventricle during development • Presents in adolescence or adults

• No hydrocephalus • Recurrent headache and neck pain • Urinary frequency • Progressive spasticity

SEIZURES

Definitions • Seizures triggered recurrently from within the brain versus somatic disorders that may trigger a seizure from outside the brain • Epilepsy is present when at least two unprovoked seizures occur more than 24 hours apart.

Febrile seizures An 18-month-old child is brought to the emergency center after having a generalized tonic-clonic seizure that lasted approximately 5 min. The parents say that the child had been previously well but developed cold symptoms earlier today with a temperature of 39°( (102°F). • 9 months to 5 years of age; peak at 14-18 months • Usually positive family history • Temperature usually increases rapidly to >39°C (102°F) • Typical: generalized tonic-clonic seizures, 15 minutes, more than one in a day, and focal findings • May occur in the future with fever • Simple febrile seizure has no increased risk of epilepsy--risk for febrile seizures is increased with atypical seizure, family history of epilepsy, initial seizure before 9 months of age, abnormal development, or preexisting neurologic disorder - Workup/Evaluation o Must determine cause of fever and rule out meningitis o

-

No routine labs, no EEG, no neuroimaging

Treatment~ontrol fever

~PL~ MEDICAL

n7

USMLE Step 2: Pediatrics

Partial Seizures Simple • Asynchronous tonic or clonic movements; most of the face, neck, and extremities; average duration 10-20 seconds • Some have an aura and may verbalize during the attack; no postictal period • EEG-spike and sharp waves or multifocal spikes • Treatment-phenytoin, carbamazepine; levetiracetam, zonisamide as adjuncts if needed

oxcarbazepine, or

Complex seizures Impaired consciousness at some point, may be very brief; one-third with aura (always indicates focal onset) • Automatisms common after loss of consciousness (lip-smacking, chewing, swallowing, increased salivation) • Interictal EEG---tmterior temporal lobe shows sharp waves or focal spikes • MRI-many will show abnormalities in temporal lobe (sclerosis, hamartoma, cyst, infarction, arteriovenous malformation [AVM], glioma) • Treatment-carbamazepine (drug of choice), gabapentin (add-on drug for refractory),lamotrigine (add-on), tiagabine (add-on), topiramate (adjunct for refractory)

Benign centrotemporal (Rolandic) epilepsy • Repetitive spikes from Rolandic gyri with a normal background • No neuropathic lesion, excellent prognosis • Occurs at 2-14 years of age; peak at 9-10 years of age • Normal history and physical, often positive family history

• Partial seizure, most often of the face; simple or complex, and may generalize • No anticonvulsants unless frequent seizures; carbamazepine (drug of choice); spontaneous remission at 14-16 years of age

Generalized Seizures Absence (petit mal) • Sudden cessation of motor activity or speech with blank stare and flickering eyes • More in girls; uncommon 39°C?

• Urine culture • Stool culture • Chest x-ray

~

I

• Blood culture (in all with T >39°C or T >39°C and WBC >15,OOO/mm3) Afebrile and well

S. pneumoniae and all other bacteria Persistent fever

S. pneumoniae Afebrile Well appearing

~

r-

Figure 22-1. Management of Previously Healthy 91-Day-Old to 36-Month-Old Child With Fever Without a Source

f""'>.. ("""

~ MEDICAL

243

USMLE Step 2: Pediatrics

MENINGITIS A 6-year-old presents to the physician with the chief complaint of headache, vomiting, neck stiffness, and photophobia. Physical examination reveals an ill-appearing child unable to flex his neck without eliciting pain. Kernig and Brudzincki signs are positive.

Acute Bacterial (Older Than a Neonate) • First 2 months of life represent maternal vaginal flora-group B Streptococcus,

E.coli, Listeria • Age 2 months to 12 years-So pneumoniae (peaks in first 2 years), N. meningitidis (sporadic or in epidemics; direct contact from a daycare center or a colonized adult family member; increased in college freshmen living in dorms), and HiB (now uncommon due to many years of immunization) • Pathology-meningeal inflammation and exudate

Note Infants do not have positive Kernig or Brudzinski sign in meningitis but will have bulging fontanelles on physical examination.

-

Most from hematogenous spread, initially from bacterial colonization of nasopharynx, and a prior or current viral infection may enhance pathogenicity

-

Rarely from an infection at a contiguous site (sinusitis, otitis media [OM], mastoiditis, orbital cellulitis)

• Clinical presentation - Less common-dramatic, sudden, rapid deterioration over hours to a day, with shock and death -

More common-several days with fever, lethargy, irritability, anorexia, nausea, vomiting Then meningeal irritation (photophobia, neck and back pain, and rigidity)

-

o

Kernig sign: flexing of the hip 90 degrees and subsequent pain with leg extension

o

Brudzinski sign: involuntary flexing of knees and hips after passive flexing of the neck while supine

Increased ICP suggested by headache, emesis, bulging anterior fontanelles, oculomotor or abducens palsies, hypertension with bradycardia, apnea, decorticate or decerebrate posturing, stupor, coma

• Diagnosis-need lumbar puncture (lP) and blood culture in all (90% have a positive blood culture); See Table 22-2. Must memorize. -

244 ~PLA'!y

MEDICAL

Contraindications to immediate LP o

Evidence of increased ICP

o

Severe cardiopulmonary problems requiring resuscitation

o

Infection of skin over site

o

Do not delay antibiotics for the CT scan.

f"'l'"

Infectious Disease

f"'l'" ~

r'" f"'l'"

Table 22-2. CSF Findings in Various Types of Meningitis "'~--".'~--""-"'-"'''--''-------'\

Pyogenic

Partially'D:eated

Granulomatous

Aseptic

Neighborhood Reaction~

I i l

200-5,000

200-5,000

100-500

100-700

100-500

, Cytology

PMN

MostlyPMN

L

PMNL

Variable

I

Low

Low

Low

Normal

Normal

High

High

High

Slightly high

Variable

I j ,i

Positive

Variable

Negative

Negative

Negative

1

Culture

Positive

Variable

Positive

Negative

Negative

I

I CIE or LA

Positive

Positive

Negative

Negative

Variable

I

High

High

Normal

Variable

I

Cells/mL

Glucoset

I Protein

I Gram stain I

I

I Pr:ssure

High

------,-,--

-,,.

I

1 ~

f

Definition of Abbreviations: CIE, counterimmunoelectrophoresis; L, lymphocyte; LA, latex agglutination; PMN, polymorphonu-

clear neutrophil.• Neighborhood reaction refers to a localized focus of infection near the subarachnoid space that may spill some products of inflammation into the CSF. Such a site could be a brain abscess, an epidural abscess, sinusitis, or mastoiditis. tCSF glucose concentration should be considered in relation to blood glucose concentration; normally CSF glucose is 50-70% of blood glucose.

• Treatment Initial empiric treatment-vancomycin plus either cefotaxime or ceftriaxone -

Specific treatment after identification of organism (if sensitive): o

S. pneumoniae: penicillin or third-generation cephalosporin for 10-14 days

o

N. meningitidis: penicillin for 5-7 days HiB: ampicillin for 7-10 days If pretreated and no organism is identified: third-generation cephalosporin for 7-10 days Gram-negative (E. coli): third-generation cephalosporin for 3 weeks, or for at

o o

o

least 2 weeks after sterilization -

Data support the use of IV dexamethasone added to initial treatment of meningitis due to HiB. Decreased incidence of fever, elevated CSF protein, and 8th cranial nerve damage.

• Complications Increased ICP with herniation and seizures Subdural effusion, especially in infants with HiB, can cause seizures, persistent fever; drain if symptomatic. -

Cranial nerve palsies, stroke, thrombosis of dural venous sinuses Most common sequelae is hearing loss (especially with pneumococcus) Less common: mental retardation, developmental delay, visual impairment

• Prevention Chemoprophylaxis with rifampin for N. meningitidis and HiB, but not for

s. pneumoniae

All dose contacts regardless of age or immune status

~PLA'!y MEDICAL

245

USMLE Step 2: Pediatrics

Acute Meningococcemia • Initially may mimic a viral disease (nonspecific) • Characteristic meningococcal rash often seen before more serious signs develop • If fulminant-rapid progression: septic shock, disseminated intravascular coagulation, acidosis, adrenal hemorrhage, renal and heart failure • Any organ can be affected by vasculitis and thromboembolic disease. • Petechiae and purpura ± meningitis = purpura fulminans • Chemoprophylaxis for close quarters (dorms, army barracks)

Viral (Aseptic) Meningitis

Note Anything that suggests temporal lobe involvement (Le., focal seizures, a scan, MRI, and EEG findings localized to the temporal lobe) is highly suspicious for herpes simplex virus.

• Affects meninges and brain tissue variably; most are self-limited; person-to-person contact in summer and fall; most are enteroviruses Arbovirus = arthropod-borne viruses; vectors are mosquitoes and ticks after biting infected birds or small animals; spreads to humans and other vertebrates Rural exposure more common Herpes simplex: focal; progresses to coma and death without treatment -

Varicella zoster: most common presentation is cerebellar ataxia and acute encephalitis. Cytomegalovirus: in immunocompromised, disseminated disease; or congenital infection but not in immunocompetent host

Note Encephalitis = meningitis + mental status changes Consider drug ingestion in differential diagnosis

Epstein-Barr virus (EBV), mumps: mild but with 8th -nerve damage • Clinical Headache and hyperesthesia in older children Irritability and lethargy in infants Fever, nausea, vomiting, photophobia, and neck, back, and leg pain Exanthems, especially echovirus and coxsackie, varicella, measles, and rubella • Complications Guillain-Barre syndrome, transverse myelitis, hemiplegia, cerebellar ataxia Most completely resolve without problems except for the neonate with HSV (severe sequelae) • Diagnosis -

PCR of CSF is the best test.

- Viral culture • Treatment-supportive, except acyclovir indicated for herpes simplex virus (HSV)

246 ~PL~

MEDICAL

""""". ~

Infedious Disease

PERTUSSIS A lO-month-old child who is delayed in immunizations presents with a paroxysmal cough. The patient appears ill and continuously coughs throughout the examination. The patient has facial petechiae and conjunctival hemorrhages. In addition, the patient has post-tussive emesis.

Note

Pertussis Early treatment may alter the course of disease. Treatment decreases communicability.

• Cause-Bordetella pertussis -

Endemic; very contagious; aerosol droplets

• Neither natural disease nor vaccination provides complete or lifelong immunity; wanes after 3-5 years and immeasurable after 12 years -

Subclinical reinfection

-

Coughing adolescents and adults are major reservoirs.

• Clinical presentation of whooping cough -

Catarrhal phase (2 weeks)-coldlike symptoms (rhinorrhea, conjunctival injection, cough)

-

Paroxysmal phase (2-5 weeks)-increasing to severe coughing paroxysms, inspiratory "whoop" and facial petechiae

-

Convalescent phase-2 weeks of gradual resolution of cough

• Diagnosis -

History may reveal incomplete immunizations

-

Gold standard is culture (nasopharyngeal aspirate or cough). PCR

-

Direct fluorescent antibody test may be helpful in those with previous history of antibiotic usage. Chest x-ray is usually normal.

-

Leukocytosis with lymphocytosis

• Treatment -

Supportive care

-

Always treat if suspected or confirmed: erythromycin for 14 days (other macrolides with similar results) only decreases infectious period of patient; it may shorten the course of illness; also treat all household members and any close contacts

~ MEDICAL

247

USMLE Step 2: Pediatrics

Bartonella (Cat-Scratch Disease) A 6-year-old presents with a swollen 3x5-cm tender, erythematous, anterior cervical neck node. He denies a history of fever, weight loss, chills, night sweats, or sore throat. The patient's pets include a kitten, a turtle, and goldfish. • Etiologic agent-Bartonella henselae Most common cause of lymphadenitis lasting >3 weeks -

Cutaneous inoculation (arthropod borne by cat flea); kittens transmit better than cats

-

Incubation period 3-30 days

• Clinical presentation

Note Parinaud oculoglandular syndrome consists of: - unilateral conjunctivitis - preauricular lymphadenopathy - cervical lymphadenopathy - occurs after rubbing the eye after touching a pet

-

Other nonspecific findings: fever, malaise, headache, anorexia

-

Less common: abdominal pain, weight loss, hepatosplenomegaly, osteolytic lesion

-

Atypical presentation: Parinaud oculoglandular syndrome

• Diagnosis Clinical with history of scratch from cat -

Tissue: peR and Warthin-Starry stain (shows gram-negative bacilli)

-

Serology: variable immunoglobulin IgG and IgM response

• Treatment-Antibiotics questionable (usually self-limiting and resolves in 2-4 months); aspiration oflarge and painful lesions

Note Mantoux Test Reactions - A reaction of >5 mm is positive in those who have been exposed to TB or are immunocompromised. - >10 mm of induration is positive in high-risk populations. - For low-risk persons, >15 mm is positive. - Previous vaccination with bacilli Calmette-Guerin (BCG) may cause a falsepositive reaction. - Patients who are immunocompromised, are malnourished, or received live-virus vaccines may have afalse-negative reaction.

248 ~PLA'!y

One or more 3- to 5-rom red to white papules along the linear scratch plus hallmark: chronic regional lymphadenitis

MEDICAL

MYCOBAaERIA

Tuberculosis A lo-year-old child is referred by the school nurse because of a positive tuberculin skin test. The patient has been well, without any associated complaints. • M. tuberculosis • High-risk reservoirs-recent immigrants, low SES, HIY, elderly • Primary complex-affects the lung with local infection with hilar adenopathy Latent infection-reactive TB skin test and absence of clinical or radiographic findings • Diagnosis - Skin testing o Delayed hypersensitivity-Mantoux (PPD) test ~

o

(+) most often 4-8 weeks after inhalation Positive reaction (5, 10, 15 rom), depending on risk factors (see margin note)

"""

I

Infectious Disease

-

Best-if can get sputum o Otherwise-3 consecutive early A.M. gastric aspirates (still only 50%, even withPCR) o A negative culture never excludes the diagnosis.

• Clinical Presentation -

Primary TB usually asymptomatic in children; healthy host will wall off the organism

-

Infants more likely to have signs and symptoms

-

Occasionally-low-grade fever, mild cough, malaise, i.e., flulike symptoms that resolve in 1 week

-

Reactivation rare, (esp. if acquired r-

5i'

f

r

~

1

USMLE Step 2: Pediatrics

OTHER VIRAL DISEASES Epstein-Barr Virus A 22-year-old college student presents to the clinic complaining of fever, fatigue, and sore throat that have not improved for the last 2 weeks. Physical examination reveals generalized adenopathy most prominent in the anterior and posterior cervical nodes. • Etiology/Risk Factors - Infectious mononucleosis (90%) -

Infectious Mononucleosis Triad

First human virus to be associated with malignancy o

Nasopharyngeal carcinoma

o

Burkitt lymphoma

o

Others: Hodgkin disease, lymphoproliferative disorders, and leiomyosarcoma in immunodeficiency states

o

Transmitted in oral secretions by close contact (kissing disease); intermittent shedding for life

o

Incubation period: 30-50 days; most cases in infants and young children are clinically silent

1. Fatigue

2. Pharyngitis 3. Generalized adenopathy

• Clinical presentation -

Older with insidious, vague onset: prodrome for 1-2 weeks with fever, fatigue, headache, myalgia, sore throat, abdominal pain

-

On physical examination-generalized lymphadenopathy (most in anterior and posterior cervical and submandibular nodes; less often in axillary, inguinal, epitrochlear nodes), splenomegaly (half the cases; 2-3 em), and a small number with hepatomegaly

-

Moderate to severe pharyngitis with tonsillar enlargement occasionally exudative

-

Small number with rashes (maculopapular); most will have rash if treated with ampicillin or amoxicillin (immune-mediated vasculitic rash)

• Diagnosis - Atypicallymphocytosis

Note Any question on the Step Two exam that mentions onset of rash after taking ampicillin or amoxicillin for URI-related symtoms, think mono first.

-

Mild elevation in hepatic transaminases

-

Heterophile antibodies (Monospot test)

-

IgM to viral capsid antigen is the most valuable and specific.

• Treatment - Rest and symptomatic therapy -

No contact sports or strenuous activity with splenomegaly

-

Short course of steroids for complications: incipient airway obstruction, thrombocytopenia with hemorrhage, autoimmune hemolytic anemia, seizures, meningitis

• Complications - Splenic hemorrhage or rupture (very rare); most in second week, most with trauma

260 ~PLA'!y

MEDICAL

AIllI.,

Infedious Disease

-

Swelling of tonsils and oropharyngeal lymphoid tissue: airway obstruction

-

Neurological complications rare

-

Guillain-Barre syndrome or Reye syndrome

-

Aplastic anemia

-

Interstitial pneumonia

-

Myocarditis Most cases resolve in 2-4 weeks; some disability that comes and goes for a few months is common; and there may be fatigue for a few years, but there is no evidence of second attacks from EBV and no evidence that EBV is related to chronic fatigue syndrome

Influenza Viruses A 14-year-old girl is brought to the physician's office by her mother. She has a 2-day history of fever of 39.7°( (103.S°F), headache, sore throat, refusal to eat myalgia, chills and non-productive cough. Her current temperature in the clinic is 39.3°( (102.8°F). • Etiology/Risk Factors -

Three types-A, B, and C, with A and B being the primary pathogens of epidemic disease

-

Migratory avian hosts may be responsible for spread.

-

Annual spread between Northern and Southern hemispheres; origin of new strains often traced to Asia

-

One or two predominant strains spread annually

-

Attack rate highest in the young; colder months in temperate climates

-

Transmission by small particle aerosol

• Clinical presentation -

Predominantly respiratory illness

-

Abrupt onset with coryza, conjunctivitis, pharyngitis, and dry cough Prominent systemic signs: fever (2-4 days), myalgia, malaise, headache

• Diagnosis - Virus can be isolated from nasopharynx early in course. -

Rapid diagnostic test: EliSA Can be confirmed serologically with acute and convalescent titers

• Treatment Rest and adequate fluid intake -

Control of fever

-

Antiviral drugs: decrease severity and duration if administered within first 48 hours of symptoms

• Complications-otitis media, pneumonia; secondary bacterial infection, myocarditis

~APLA'!y MEDICAL

261

USMLE Step 2: Pediatrics

Acquired Immunodeficiency Syndrome (AIDS) An 18-month-old has failure to thrive and developmental delay. The patient also has a history of recurrent ear infections, oral thrush, and chronic diarrhea. The patient on physical examination today is noted to have lymphadenopathy. • Etiology/Risk Factors -

Most are children born in developing countries; acquired at birth from an HIVpositive mother

-

Breast feeding in developing countries is an important route of transmission.

-

Pregnant females in United States and other developed countries are routinely screened for HIV infection in prenatal labs, unless the patient refuses. o

Early treatment and prevention of neonatal infection through anti-retroviral therapy and preventive measures during delivery/postpartum period

• Clinical presentation -

HIV-infected newborns o

Rapid onset of symptoms and AIDS in first few months of life

Initial symptoms may include o

Lymphadenopathy

o

Hepatosplenomegaly

o

Failure to thrive

o

Chronic diarrhea

o

Interstitial pneumonia

o

Oral thrush

More common in children than adults: recurrent bacterial infections, chronic parotid swelling, lymphocytic interstitial pneumonitis, early progressive neurological deterioration • Classification of disease based on clinical status and degree of immunologic impairment Category A (mild symptoms; at least two): lymphadenopathy, parotitis, hepatomegaly, splenomegaly, dermatitis, recurrent or persistent otitis media/sinusitis Category B (moderate symptoms): lymphocytic interstitial pneumonitis, oropharyngeal thrush for >2 months, recurrent or chronic diarrhea, persistent fever >1 month, hepatitis, recurrent HSV stomatitis, esophagitis or pneumonitis, disseminated varicella, cardiomegaly or nephropathy Category C (severe symptoms): two serious bacterial infections in a 2-year period, esophageal or lower respiratory tract candidiasis, cryptococcosis, cryptosporidiosis >1 month, encephalopathy, malignancies, disseminated mycobacterial infection, Pneumocystis carinii pneumonia (PCP), cerebral toxoplasmosis, severe weight loss

262 ~PL~

MEDICAL

Infedious Disease

• Infections -

Recurrent bacterial infections with encapsulated organisms and other grampositive and gram-negative organisms

-

Opportunistic infections; most common is PCP (onset of fever, tachypnea, dyspnea, and marked hypoxemia)

-

Mycobacterium avian-intracellulare complex: disseminated disease in severely compromised

-

Oral candidiasis and other invasive fungal infections

-

Viral infections, especially herpes group

• Other problems CNS disease Cardiomyopathy Enteropathy Wasting syndrome, nephropathy -

Many cutaneous manifestations

-

All hematologic manifestations, malignancies

• Diagnosis

-

HIV-DNA by PCR Maternal HIV IgG antibodies cross the placenta o

Screen will be positive in all newborns up to 18 months of age.

In any child >18 months of age: test for infection through IgG Ab by ELISA and then confirm with Western blot to establish the diagnosis. • Treatment-infants born to HIV-infected mothers -

Mother o

-

Should be on perinatal triple anti-retroviral therapy

Infant o

Should be started on ZDV (birth) until neonatal disease is excluded

o

Also start PCP prophylaxis (TMP-SMZ) at 1 month until disease excluded

o

Follow CBC, platelets, CD4 and CD8 counts

o

With symptoms or evidence of immune dysfunction, should be treated with antiretroviral therapy, regardless of age or viral load

• Prognosis -

Best single prognostic indicator is the plasma viral load.

-

Mortality higher with CD4 count '~

!

__

M~'

""•.v

,~._•• "

Poison/Toxic Sign

Antidote

Acetaminophen

N-acetylcysteine

! Anticholinergics

Physostigmine sulfate

: Anticholinesterases

Atropine sulfate Pralidoxime (2-PAM) chloride

j Benzodiazepines

"I

1 1

,

I )

i

i

Flumazenil

I

, Carbon monoxide

Oxygen

i Cyanide

Amyl nitrite Followed by sodium nitrite

I

i I Digoxin

Antidigoxin Fab fragments

,1

\ Ethylene glycol

Ethanol

,

t Extrapyramidal signs

Diphenhydramine hydrochloride

Followed by sodium thiosulfate

I

Benztropine mesylate Heavy metals (e.g., arsenic, copper, gold, lead, mercury)

Chelators Calcium disodium edetate (EDTA) Dimercaprol (BAL) Penicillamine 2,3-dimercaptosuccinic acid (DMSA, Succimer)

: Heparin

Protamine sulfate

: Iron

Deferoxamine mesylate

Isoniazid (INH)

Pyridoxine

Methanol

Ethanol

Methemoglobinemia

Methylene blue

! Nitrites Opioids

I

Methylene blue Naloxone hydrochloride

j

\ I

: TCAs/Salicylates

Sodium bicarbonate

: Warfarin and related drugs

Vitamin Kl (phytonadione) Fresh-frozen plasma

I

I

~ MEDICAL

281

USMLE Step 2: Pediatrics

ACCIDENTS/EMERGENCIES Head Trauma A5-year-old fell approximately 6 feet from a tree and is brought to the emergency center because he had loss of consciousness at the scene for 1 minute. The patient is awake and alert on arrival, and his Glasgow Coma Score is 15. The patient has an obvious deformity of his right forearm and some bruises. Otherwise, the physical examination is unremarkable.

Note Intubation is indicated if the GCS isS8.

• Major causes of head trauma -

Motor vehicle accidents

-

Sports

-

Recreation Violence

• Presentation-depends on injury

-.

• Physical examination -

Linear/depressed skill fracture

-

Basilar skill fracture o

Battle sign

o

Raccoon eyes

o

Hemotympanum

o

CSF rhinorrhea

o

Otorrhea

Types of head injuries • Concussion-brief unconsciousness, then normal arousal • Grades

-

Grade 1: Confusion only Grade 2: Confusion + amnesia only Grade 3: Confusion + amnesia + loss of consciousness

• Recommendations

-

Grade 1: Return if asymptomatic for 20 minutes Grade 2: Return in 1 week after no symptoms for 1 week Grade 3: Return in 1 month after no symptoms for 1 week

Other head injuries • Epidural hematoma -

LOC ~ lucid interval --+ LOC

-

Lens-shaped hemorrhage on CT scan

• Subdural hematoma-crescent shaped • Cerebral contusion-punctate hemorrhage • SCIWORA-spinal cord injury without radiographic abnormality

282 ~PL~ MEDICAL

-,

Introduction to Poisonings, Ingestions, and Accidents

• Tests - Head CT scan -

Cervical films

-

MRI

Drowning A 15-month-old was found with his head stuck in a bucket filled with cleaning agent. The mother says that she received a telephone call while mopping the floor, but that she was only speaking on the telephone for 5 minutes. • Etiology/Risk Factors -

Highest risk in those 1-4 years old and 15-19 years old

-

Gender-MALES

-

Race-blacks

-

Drugs often implicated

• Most are freshwater -

Freshwater drowning has higher morbidity than saltwater drowning; washes out pulmonary surfactant

-

Saltwater drowning results in more pulmonary edema

• Sites - Pools Canals -

Hot tubs

-

Buckets

-

Ocean

• Dry versus wet drowning • Anoxic-ischemic injury of many organs • Treatment is supportive. • Prognosis-hard to predict -

25 minutes submersion, prognosis is bad

-

GCS >6 more favorable

-

Need for resuscitation at scene

Burns A 2-year-old comes to the emergency center after being splashed with hot coffee that fell off the table when he pulled the tablecloth. He has first- and second-degree burns. • Suspect abuse whenever history does not match physical examination • Scalding burns account for >85% of clinical burns in kids 17 years) o

Less self-centered

o

Relationships with individuals rather than groups

o

Contemplate future goals, plans, and careers

o

Idealistic; have a sense of right and wrong

Table 24-1. Tanner Stages of Development ,,-'~-~~'~',--

Stage

l I 'II III

"'--"~"'"

'''''''''''''''~~'~

... v

~~

_,~_,~~,

"-po"

~~. N'~_~"

""'"~~'"'"

,

,~.~"

....

__

,h"'""A~~_~

''''~'''~'''''''''_'v.~

Female

Both

Male

Breast

Pubic hair

Genitalia

Preadolescent

None

Childhood size

Breast bud

Sparse, long, straight

Enlargement of scrotum/testes

Areolar diameter enlarges

Darker, curling, increased amount

Penis grows in length; testes continue to enlarge

IV

Secondary mound; separation of contours

Coarse, curly, adult type

Penis grows in length/ breadth; scrotum darkens, testes enlarge

V

Mature female

Adult, extends to thighs

Adult shape/size

1

, i

• Puberty -

Variability in onset, duration

-

Irreversible

-

Physical reflects hormonal

No variability in order of changes

• Variants of development are normal and most cases only require reassurance from the physician to the patient and their family.

286 ~

MEDICAL

-

Breast asymmetry and gynecomastia often seen in males at Tanner stage 3

-

Irregular menses due to anovulatory cycles seen in females starting to menstruate

1""IIIi\,

Adolescence

Sexually Transmitted Diseases Gonorrhea A 16-year-old girl presents to her physician because of fever, chills, pain, and swelling in the small joints of her hands, and a maculopapular rash on her upper and lower extremities. • Neisseria gonorrhoeae usually infects mucosal membranes of the genitourinary tract

Note

and less commonly the oropharynx, rectum, and conjunctiva. • Clinical presentation includes urethritis, cervicitis, and dysuria. • Asymptomatic patients are at higher risk for dissemination, including fever, chills, and arthritis.

Untreated GC/Chlamydia may result in PID and/or infertility (due to tubal scarring).

• Physical examination -

Males present with dysuria and purulent penile discharge.

-

Females present with purulent vaginal discharge, cervicitis, abdominal pain, and/or dysuria. Rectal gonorrhea may present with proctitis, rectal bleeding, anal discharge, and/or constipation.

• Tests - Culture from discharge Blood cultures if dissemination is suspected -

Gram strain may show intracellular diplococci.

• Check for other STDs, including syphilis and HIV infection. • Treat with single-dose ceftriaxone or single-dose azithromycin; treat partners. Alternatives include doxycycline for 7 days (not in children 4.5

>5